4AGE 16V Build, Take 2: 200hp "Streetable" Track Toy

mr2tailbreaker · Dec 10, 2014

I've been meaning to start this thread for weeks, but life can get unexpectedly overwhelming. So, things have been delayed.

But I want my 2 back, and the rapidly approaching holiday break is going to be my best opportunity to get back on track. So, I'm finally creating this discussion, firstly to help me plan how to get as close to 200hp as possible while not getting "crazy" on expenditures (i.e. want to avoid costly parts like forged custom rods, etc), and secondly of course to document the project.

This build is a "Take 2" because I just rebuilt my motor a year ago, as documented here:

http://www.mr2oc.com/showthread.php?t=468649

The motor was making about 150whp on 91 octane and stock management(11:1 pistons, 264 poncams, head work, exhaust, mild tuning), lasted about 25,000 miles, over 10 months, with over 2000 miles on track bouncing off the stock limiter. One day this past August, a ring apparently failed on cylinder 2, as the motor started puking oil through the crankcase breather(heavy blowby), and cylinder 2 compression dropped dramatically. The cause is not yet clear.

For that first build, i didnt really know what I was doing (virtually all my experience was with diesel motors, and I'd never done a full rebuild), was building against the clock (a schedule of about 4 months), and started with a purely factory motor. Corners were cut, including not properly boring the block.

For this build, I will largely know what I'm doing, will be starting with a fairly well-tuned motor, and will not be giving myself artificial time constraints. I will plan to do it right, however long that takes (within reason), and will be focused on eeking out the most from the motor while staying relatively stock for components, and keeping the budget hopefully below about $1500-2000. My minimum costs are going to be a rebuild kit, boring, new oil pump, new pistons, and any other ancillary do-it-while-I'm-in-there kinda parts, which I figure is about $1000 total.

Note, I have facilities, an engine stand, and I will be doing virtually all assembly, inspection and fab work myself - only significant machine work that requires a shop will be sent out.

My previous build was making a solid 150whp(165-170hp at the crank; my previous 170-180chp estimates might have been a little optimistic).

For this build I'm shooting to build a motor capable of 200chp, when using an appropriate cam. I'm hoping to retain my 264 Poncams for the time being, which are overall great cams, and achieve around 180chp (~160whp), while retaining an option to drop in bigger cams if and when I want extra power. I still dont know if this will be doable, and if I must, I may just go straight to larger cams. But, I'm trying to keep the car still driveable/streetable, and dont want to sacrifice low end too much for the time being.

So, here is a basic summary list of where the motor is now, and where I want it to be when I'm done:

~150whp (before ring failure)
non-interference motor
11:1 pistons, 81.0mm (realize now why that diameter was a bad idea)
264 Poncams, I/E
Fidanza cam pulleys, I/E
HKS valve springs, stock valves, with 3-angle job
Factory head, pen-dye inspected, with port and chamber work done myself (not flow tested), seat inserts machined and blended/deburred
Block is basically stock, 7 rib without oil squirters, with .009inch decking (had a corrosion pit); oil return ways cleaned up
Standard Toyota head gasket
Large and heavy 42mm/20mm crank/rods, balanced, magnafluxed
Chromoly lightweight flywheel, balanced
ACL bearings, new at last rebuild
Factory Exedy clutch, replaced at last rebuild (25000 miles), balanced
Factory mamagement and rev limiter
Factory injectors (amazingly)
2.25" custom exhaust system, factory cast header
Stock intake system, including TVIS
Factory oil pump, hand ported
Twosrus oil sump baffle kit
Remote oil filter arrangement, running Toyota filters, Japanese and Thailand models
Mocal Laminova C43 "medium" oil/water heat exchanger, plumbed off hot radiator hose; -10AN plumbing
Motor was not bored, but was very close to factory specs

Known concerns/problems:
Borderline (mild) knock running 91 octane
Bores were not perfectly shaped; compression numbers were never very even; low ~85% of high.
Possible oil pressure loss at high rpms from cooling system

Where I want to be:

180hp crank (~160whp) with the existing Poncams; option to get near or above 200chp with cams.
Prefer to stay noninterference (should be no problem with existing cams) but OK to become interference to attain 200hp.
Prefer to keep existing block; will bore out for new pistons, either .25 or .50mm oversize; will seek a "hot" torque plate boring
Need new pistons; staying 11:1 or maybe a bit more (depending on cam issues); strongly leaning toward OST's new offering
Sticking with factory head gasket, giving option to run a little more compression with a HG change, head shaving, etc
Will further tune my head (porting, chamber balancing, etc)
Want to retain stock valves; will be using a set of Toda valve springs
Hoping to stick with stock management for a short while, then move to custom management to extract full performance
Expecting the motor will need to live around 8000rpm, with an eventual 9000rpm limiter
Will be wanting a better oil pump; need to determine my needs
Possible TVIS delete?
If TVIS delete, what should I do with my intake/induction system? If M.A.P. sensor, totally new induction system down the line?
I want my tailpipe emissions to be as good as I can get them, but it will not be a priority

My motor is still fully together, and will run, but not well. Some testing I want to do before tearing down my motor:

TVIS on vs off performance - TVIS delete? I figure I can do a few gtech runs to see if the TVIS is doing much for my low end with the existing set up.

I would like to test my oil pressure loss from my external oil cooler plumbing.

Any other suggestions?

IMPORTANT: Right now I have not 100% confirmed the cause of the low compression on cylinder 2. I'm confident it is probably a cracked ring, but perhaps it could be a cracked head? However there is no sign of cooling system contamination or overpressure. What else would explain high blowby and low compression? I dont think bad valve seating/sealing makes sense... Is a leak down test really worth worrying about? I'd want to do it myself - i'm not driving the car to a shop.

More to come, including edits, updates, etc...

EDIT:

Here are two plots of my existing motor before the ring failure, the higher being the best plot I ever made, with good AFRs and about 12k miles on the motor:

https://onedrive.live.com/?cid=215c...d13d921&id=215C6BF9FD13D921!1495&v=3&ithint=photo,.jpg&authkey=!ACHO0AiiRH0D3n0

https://onedrive.live.com/?cid=215c...D3n0#cid=215C6BF9FD13D921&id=215C6BF9FD13D921!1734&v=3&authkey=!ACHO0AiiRH0D3n0

I'll also add that I am a big fan of the "race car" nature of the 4A, along with its racing heritage and history (numerous calls have come up for going to a 7AGE).

oldeskewltoy · Dec 10, 2014

Wow.... tall order.... 180chp = stock valves + Poncams + stock stroke + non interference + other tidly bits

My pistons and the Pon cams may... or may not be interference... it all depends on the distance between the valve seats and the piston @ TDC.

8000 isn't a real problem... 9000 and you are really pushing things...

Get the chambers perfect.... Its likely time for a performance based valve - even though you are keeping them to stock diameters.

Oiling - as you have discovered.... track time on a 4AG really HEATS the oil. You have tried coolers... what you have yet to try is adding more volume. Adding volume will lower temps. I'm not talking a 1/2 quart... I'm talking 3 to 5 quarts. How you do it....????

Dry sump - solves all the oiling problems. I can get you a dry sump pan for under $1000.00

EDIT - http://www.mr2oc.com/showpost.php?p=5732842&postcount=869 Don't I remember you said you run the 1/4 mile in 90 something?? THAT will be your best measure as to performance before, and after.... Your new engine should push your MR2 through the traps at over 96mph

mr2tailbreaker · Dec 11, 2014

oldeskewltoy said:
...

EDIT - http://www.mr2oc.com/showpost.php?p=5732842&postcount=869 Don't I remember you said you run the 1/4 mile in 90 something?? THAT will be your best measure as to performance before, and after.... Your new engine should push your MR2 through the traps at over 96mph

From your piston thread:

mr2tailbreaker said:
Just did a few "1/4mi" runs using my Gtech. I'm just above sea level. 71F. No wind. Night time so head lamps are up. Sunroof is off and i have no engine bay underbody paneling, and so in total my aerodynamics aren't the best. Weight plus driver is ~2520lbs +/- 20lbs.

I did not launch at all, just a mildly more aggressive street start, which I'm sure counts against me pretty good. Shifts were pretty good. Just did runs on several different sections of the freeway that seemed flat and level, starting from the shoulder. And remember, my average power between shifts won't represent 150whp because I'm basically forced to short shift by the stock limiter.

Consistently getting 17.2s at 85mph. 3axis GtechPro RR, reaction time zero, rollout 9inches.

oldeskewltoy said:
... trap speed on the other hand tells me quite a bit more. and repeated trap speed helps confirm. Whatever your limitations are within reason, you are planting OVER 140whp. Yeah I know, that is what all the other bits have also said....

...

mr2tailbreaker · Dec 10, 2014

Thanks for the quick feedback. At this moment, I'm definitely still in sanity check mode, trying to figure out what is realistic for this project. One way or another I guess I'm pulling the motor for a rebuild, in about 10-12 days from now. The question is how ambitious should I be, and how realistic am I being.

$1000 for a dry sump system... eh, I'm not real excited to spend that kinda money on it unless it really looks like a requirement. For the most part, my baffled wet sump seemed to be working well on track. As we might recall, my oil temps were sitting around 270F hot (ahead of the cooler) on a pretty warm day. Pretty hot, but not scary to me with good oil... Before the Laminova I was seeing over 320F on track in cool weather. Again, I'm not opposed but I need to be convinced of a real need. Pulling apart the motor and figuring out what went wrong may factor in... My main oiling concern is sufficient flow.

On overall power goals, I recall you describing more or less what would be required, in another thread around here. I will dig it up later.

Performance based valves, I'm guessing you mean like sodium filled...

I guess my main limitations right now are, I dont want to bother with the costs or troubles of oversized valves, or under-bucket shims. That's basically it. I have Toda springs, which should handle quite a bit more lift and duration than I'm running now.

I'm sure I'll run into fueling problems at some point, plus rpm limitations, so aftermarket management will pretty much be a requirement soon after I get the car running well enough on stock electronics.

One last thing, my 5 speed n/a tranny (I forget the designation, C52 I think?) seems to be in good shape, but apparently has about 200kmi on. No real signs of trouble though. Shifts and runs fine, far as I can tell. But I'm wondering if I should do a preventative rebuild of it, or just wait for it to break later before doing a rebuild...

mr2tailbreaker · Dec 16, 2014

mr2tailbreaker said:
...

On overall power goals, I recall you describing more or less what would be required, in another thread around here. I will dig it up later.
...

It was in your piston thread:

oldeskewltoy said:
200hp... REALLY?
...

200hp on 16V using stock valves.... and on stock rod length, stock stroke... is going to require RPMs of 9000+, a carefully ported head, cam lifts of at least 9mm, a static CR of around 12.4ish to 1. The significant powerband of this engine will begin @ about 4500 and run to 9000+

Cost to build - $8000+ (mostly because a dry sump oiling system is HIGHLY recommended)

Now.... for sake of discussion... add in an O/S valve head... and a 7A block/stroke and you can likely shave the dry sump out of the equation. Also you can reach 200hp on a O/S valve 7A with the pon cams and valvetrain you currently have. powerband would be from 3200 to 8000

yoshimitsuspeed · Dec 10, 2014

Just eyeballing OSTs pistons I am quite confident they would not be non interference. That's assuming stock HG, and everything else stock which puts you at 10.8:1? If I remember right.
Thinner HG puts the valves closer to the piston, shaved deck or head puts the valves closer.

Any way you cut it I believe you are going to need to give up on non interference. You are going to need more compression and more cam to hit your goals. There are some longer duration cams with no more lift than the poncams but I really don't see the point of going much over 264 without adding more lift.
I designed those pistons you are using in CAD so they should be very close but I did leave some margin for error.
One thing you could do before you break down the motor is put the pistons at TDC then use a dial indicator to measure how far the valve travels down before hitting the piston. You would want to do this for both intake and exhaust.
This way we would know exactly what your motor has.
The Kelford 193-B has about 1.3mm more lift on the intake side.
I designed those pistons without a headgasket in CAD which means it should really be 1.2mm further down than it absolutely needs to be but then we need to subtract .7mm for rod stretch. Anyway it would be really interesting to see how the real world compares to the theoretical it was designed around.

OST seems to be a lot more comfortable shaving the head a ton to gain compression. Personally I much prefer to keep it to a minimum and design a piston to hit the compression you want. This keeps the cylinder geometry, cam timing and everything else as close to factory nominal as possible.
You are going to want more compression than you currently have but OSTs piston starts with a good bit less.

This piston was made for a 304 cam, oversized valves and with 13.5:1 compression.

It would be easy to tweak that design a little to be a little more ideal for your build. Knock the compression down a little and if you don't want to go oversized valves we could make the reliefs a little smaller. Leaving them big would allow you to go with bigger cams and or valves in the future without needing to change pistons though.

I really want to see how those 193:b do with like 12:1 compression. I think those would get you a good bump in power while maintaining a nice broad power band. A slightly bigger cam may allow you to make a little more power but I like the fact that those have been designed with a big power curve specifically in mind.

I would do cams and pistons at the same time. To make as much power as possible you will want as much compression as possible and a bigger cam will allow you to run more compression so if you get pistons that can run on the poncams they will be a little weak on a bigger cam. Unless you planned a thicker HG while they were on the poncams then went thinner with the new cam. I would rather plan to run the thicker HG with your inital setup because that allows you to go thinner if you go with bigger cams or even if you get your tune dialed in to the point where you want to bump it up a little more.

yoshimitsuspeed · Dec 10, 2014

As for the oil pump, I have talked to racers who have run the stock pump at 8500 for extended periods. From what I have heard is after a little while they tend to start breaking down. I believe it may partially be due to cavitation and pitting on the gear seems to support this theory. It's rare for 8500 to rapidly damage the gear but over time they are known to fail. These same sources switched to the Toda gear and say they can run all day long at 8500 with some time a good bit over that. 9k shouldn't be a problem but I wouldn't really go above that.
http://www.matrixgarage.com/products/toda-4ag-heavy-duty-oil-pump-gear
With anything over 8500 I would definitely start looking at block reinforcement. Keeping it under 9000 RPM ladder caps would likely be plenty.
I have just come out with my own design that is a little cheaper than Tomei or MRP.
http://www.matrixgarage.com/products/matrix-garage-crank-ladders

jsneeb · Dec 11, 2014

Any reason you don't want to go with a turbo set up? I mean 200 hp will be very attainable, very reliable, You will have to stretch the budget though especially since you need to do motor work anyway.

But a mid/high compression and low boost set up would suit the 4age pretty well.

If you are not limited by time you can source most of the parts, including turbo, of some parts car like a Subaru, Nissan, or late 90's Saab something for dirt cheap.

oldeskewltoy · Dec 11, 2014

As to the dry sump... the PAN is a bit less than a $1000... the rest of the system will likely run you a couple grand more.... just saying... didn't say it was YOUR answer... just it is the BEST answer to oiling in a 4AGE.

As to performance valves... I mean something designed for performance purposes. OEM valves are pretty good, but a nice swirl finished valve will add a bit more flow in the head.

You will also want to push your exhaust ports out beyond the stock exhaust gasket (33mm). Tomei and Toda both offer larger exhaust gaskets. I'd push the port outlets to about 35-36mm.

As to pistons.... this build needs something built for it... you need the head done... chamber volumes equal, a known block deck, THEN have pistons made to the final specifications. The crown, or dome design matters little at this point... except you want it as tight as possible...

edit -

As to opinions on head thickness... it isn't my opinion (and/or collection of "facts"), or yoshi's... The heads I SEE @ Loynings are typically decked to the intake seat!... Now it is O/S seats, and so that does make it a bit bigger then decking a head to the stock seats... but shrinking the chamber is something I see in EVERY Loynings head...

5 examples right here........

2nd edit -

the TVIS manifold will not allow the air volume you will need. It MIGHT if it gets Extrude Honed... but the stock TVIS intake manifold will be a restriction

mr2tailbreaker · Dec 11, 2014

Yeah, I just dont want to do turbo. Turbo is "easy" not nearly as challenging or interesting, and I just want a responsive N/A high rpm screamer. I've had turbo cars all my life. I like instant throttle response, especially in a car this light and tight. I have no acceleration or power to weight target. I just want to squeeze as much out of a N/A 4AGE as I can without breaking the bank too much. Also, within limits, N/A will just be more reliable IMO, although I agree maybe not at certain power levels.

yoshimitsuspeed · Dec 11, 2014

I'm pretty sure we have butted heads on the NA vs boost thing so I won't go into detail or a long rant but a low boost high comp motor with a tiny turbo would spool so dang fast you wouldn't know it was there.

mr2tailbreaker said:
Also, within limits, N/A will just be more reliable IMO

But I do want to chime in and say I 100% disagree with this.

A 200 HP turbo 4A isn't even breaking a sweat. It could rock that all day every day.
Stock redline, more mid range power, all means more time spent at lower RPMs. smaller cams and softer springs mean less valvetrain wear etc.
Power for power, dollar for dollar the turbo motor will tend to be more reliable.
Assuming of course tuned and treated right.

mr2tailbreaker · Dec 11, 2014

I hear you. Yeah, I agree, that's sorta why I added that caveat. I agree as power gets around and above 200hp on these motors, reliability does become a problem, I'm sure.

No doubt for the money, turbo is the way to go. And that's the thing, it's "easy" like I said. I like the challenge of building a tuned piece of machinery, and while turbo lag may be fairly trivial, I'd still rather have no turbo. Plus the plumbing and extra heat back there, where I already have external oil plumbing planned... I'm ok spending a bit of money to see what I can achieve without the turbo.

If I were going for outright acceleration, turbo would be the obvious choice. And if I had plenty of money and space and time, I might even wanna do a separate turbo AW11.

I dunno, call me silly, but n/a is kinda "new to me" and I'm loving it so far. I'm gonna rebuild this more or less "as is" but I'm gonna try to squeeze more out of it in the process. Turbo feels like sorta a big departure to me from what I had in mind for the car.

I added it to the list above - with a TVIS delete, how much more pressing would a custom induction arrangement be? I rather like keeping my bay looking stock.

yoshimitsuspeed · Dec 11, 2014

Have you thought about going with a smallport head?
This would allow you to run a stock SP mani. A custom mani or ITBs would be better but I'm not sure if the benefits would justify the cost but I do think you are getting into the ballpark where it may.
I do think a SP head and mani would be better than a LP head and mani and it would keep your stock look.

mr2tailbreaker · Dec 11, 2014

I havent ruled it out. It comes down to cost and trouble of sourcing a good one, I guess. I have a fair bit of work into this big port head, and it seems to perform pretty good. The guides are good and the head is "clean." I will keep it in mind. Open to inputs/insights.

mike555 · Dec 11, 2014

Sorry if this was mentioned before...But why aren't you just going with a Black top 20v??

yoshimitsuspeed · Dec 11, 2014

mike555 said:
Sorry if this was mentioned before...But why aren't you just going with a Black top 20v???

His current build already made significantly more power than a stock 20v.

mr2tailbreaker · Dec 11, 2014

I think I was making a little more than stock 20V. Not sure how much more, but I'd be more modest about the estimate.

One major factor was that I was trying to keep things pretty stock for emissions reasons at the time. Also, the complexities of converting to the 20V motor, and parts availability.

It's my understanding the 20Vs do good for what they are, but when trying to really push above 200hp, the 16Vs are just more robust, and the extra valves really arent worth the trouble. Just my understanding. Could be wrong. I think a main advantage of the 20V is the port included angles (the orientation of the port paths as they enter and leave the combustion chambers), and of course, variable valve timing.

mike555 · Dec 11, 2014

I am impressed with the power you made without forced air.

mr2tailbreaker · Dec 11, 2014

http://forums.club4ag.com/zerothread?id=106261

I linked that toward the end of my previous build thread. That's a pretty modded BT. He's apparently making about another 10-20whp over me. But I never got around to messing with timing, fueling and revs - was limited to a stock ECU.

Chesterkv · Dec 11, 2014

Dude,

There's nothing 'street' about a 200+ horsepower n/a 16-valve.

- Chester

yoshimitsuspeed · Dec 11, 2014

Why not? It won't be as likely to last 200k miles as a stock 4A but as long as you are realistic with those expectations it should do just great.

mr2tailbreaker · Dec 11, 2014

Lol. I guess someone had to say it...

. I did hesitate, hehe. "Driveable" might have been a better term... usable power band and manageable idle character. Perhaps I should have the title edited...

yoshimitsuspeed · Dec 11, 2014

I think it's funny because people seem to think that going for big power means it will be gutless in lower revs but if you build it right this is not the case.
You will have a hard time making significantly more power than stock in the lower to mid revs but you shouldn't loose much or like with your last build hopefully gain just a little. This might seem gutless in comparison but if 3500 RPM got you around before it would get you around with a built motor just as well. Only difference is that if you really need to go you drop a gear and actually make some power.
You might have a hard time making as much lower mid range in your new build as your last but you should still make a little more than stock.

pobre · Dec 11, 2014

i could be wrong and would be interested to hear what others have to say about it but for your intake perhaps the corolla intake would work for you. this guy did it.

http://www.mr2oc.com/showthread.php?t=560913

yoshimitsuspeed · Dec 11, 2014

That's just a basic TVIS intake. If there are any differences I believe they are just aesthetic.

briansexsmith · Dec 11, 2014

Mr2trailbreaker, I think you need to ask yourself if you want a interesting project or do you just want to get the job done and have a reliable street/track car?

My car is very similar to what you want and what you want to do with it. I have around 200 HP, very good brakes, ok suspension and I drive my car to the track switch to slicks and run 100 on track miles a day. I run 12 psi on a refreshed but otherwise stock 4agze, power always available, I have full boost from 3500 to 7500 RPM if you can't find the power band you are not shifting.

I have the following bits to make it all work
small td04 turbo from a wrx (cost about $100 used)
megasquirt 3X (about $900)
ebay WTA intercooler with bosch pump ($400)
homemade manifold and exhaust ($300)
tubing and other odds and ends ($300)

This setup has been very reliable, it is not crazy stressed out like a 200 hp NA engine would be... Keep in mind formula Atlantic motors ran about this power and they did not last very long at all.

Just saying do you want something cool or do you want something that works for a long time on the track?

Interested to see how this turns out.

BTW if I where to do it all again (or maybe when my engine needs a rebuild) I would not even run a 4A, I would build a turbo setup for a 1NZ and replace used stock motors like I do a oil change.

mr2tailbreaker · Dec 11, 2014

I appreciate the warning. Crazily enough, I kinda do want an interesting "science project." But certainly I dont want the motor to fail again another year from now.

I hope people dont take it as too misleading, but if I stuck with modest improvements and ended up around 190-195hp, I think i'd be happy with that. And I have to think that that isnt such a dramatic increase over where I'm at now to be totally unreliable. I'd have to think FA engines detuned to 200hp, not seeing racing duty, will last quite a bit of time on track.

I really am just not interested in a turbo set up. If I go through with this build, and do everything the best I can, and the motor breaks down again seemingly to do with revs, then I think I'll have "learned my lesson." Maybe then I'll go turbo. But to me the N/A nature just suits this car, and my desires, and I really am interested in the challenge and coolness of it.

briansexsmith · Dec 11, 2014

^^^ Good to hear you know what you are getting into. Have fun.

sirdeuce · Dec 11, 2014

A few thoughts.
Ever consider using a 7A bottom end? Might sacrifice a little RPM, but it would make the car more street friendly with more bottom end. For the more severe use you would want aftermarket rods. I've seen these combos spun to 4AG levels without issue. Could get a core to build for cheap. Throw away everything but the crank, block and oil pan.
I agree with the suggestion of having the intake extrude honed, made a hell of a difference on my AE86 when I had it. Might consider a bored throttle body as well.
As for your possible ring failure. You said you were getting detonation. when you disassemble the engine look for collapsed or broken ring lands. If the temps spiked enough to cause the rings to expand and close the gap.
Not sure on this bit, but the AFM, I believe, should be getting close to it's max around 160-165hp level. When you get to the stand alone it would no longer be an issue though.
All in all, I do like the 'see what I can get from the stock bits' attitude! It's always tops in my book!

sirdeuce · Dec 11, 2014

Another thought. Before you do anything else, tear your engine down and inspect all the parts. If a ring did break it could render the block useless with a deep groove. I sent a PM about a block if needed.

Hardrvin · Dec 11, 2014

Going to chime in my 2cents here even though it's a dead horse. Having done the N/A vs boost game. You'll puke more money into a N/A build, feel special, take one ride in a boosted car, find out what they dropped in, and ask yourself, what was I thinking? At least, that's 9 out of 10 car people. Maybe you're that 1 in 10. And I do still think the project is neat.

Regarding your build ideas, I tend to agree with the others, wanting non-interference, stock displacement, shimmed, you're trying to have your cake and eat it to. You're going to need to make some concessions.

One limitation we face is no rocker ratio assist to get wild with the valve lift.

I'd be curious for someone to use a 7a block for the height but then do 4a crank, custom rod/piston setup to do a screamer for rev's. But not positive that's a limiter vs. valvetrain.

rmeller · Dec 11, 2014

Hardrvin said:
... use a 7a block for the height but then do 4a crank...

Not sure what you are thinking of here. The only reason I can think of for using a 7A block is to get more displacement. If you use a 4A crank, the engine will have the same displacement as an OE 4A, and the extra block height will have no benefit.

sirdeuce · Dec 11, 2014

Hardvin, the 7A block with 4A crank, long rod is a great idea! But I like the extra torque from the longer stroke. Could do 7A crank with custom pistons and rods to get a good mix from all corners!
As for the N/A-boost thing, all depends on what you want. I have both! The boost is ridiculously addicting! But sometimes the N/A is the right drug for the mood. On the 4AGE I really prefer N/A. I get my boost fix from my
Mazdasped3. The 3 gets 260/280 hp/tq to the wheels with only the cold air intake as a mod!
But for now the idea is N/A.

rmeller · Dec 11, 2014

Is the idea to reduce the piston acceleration at TDC? I can see how that would help you get to higher RPM.

oldeskewltoy · Dec 11, 2014

Long rod 4AGEs are the engines making the 260+hp. They are standard stroke, but they use longer rods, with the pin about 5.5mm further up in the piston. Piston compression height of .985", stock is 1.201"

As far as 7A... that really should have O/S valves to operate to its potential

edit - oh... did you know the 7A and 4A use very similar rod to stroke ratios??? Even though the rod to stroke ratio is considered less than ideal???

sirdeuce · Dec 11, 2014

Yes, the rod/stroke ratio is close either way. I just like the extra torque from the longer stroke. Amazing what a few mm can do. Not sure, but I think T.E.D Components works a 7A block over to have a longer rod. They don't give specifics on their site as to how, but they offer the parts/process. T.E.D. offers the 7A up to 2.0 liters. For a coffee can tightly packed with cash they can send you a complete 2.0L 7AGE!

4AGE 16V Build, Take 2: 200hp "Streetable" Track Toy

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