MR2 Owners Club Forum banner

1 - 20 of 105 Posts

·
Registered
Joined
·
1,109 Posts
Discussion Starter #1 (Edited)
ok can someone ppppllllzzzzz explain the differences between the motors??? from the information from this

4age specs

- the blue top has more power?
- the red top is a stronger motor?
how true are these

and if it is true when ordering my motor from an import shop do i need to specify that i want a specific top motor?
 

·
RIP 8/6/1948 - 9/5/2011
Joined
·
16,626 Posts
I'm sorry - but this has only been discussed about 1500 times on this very forum.

To make a long story short:

The "true" red-top is the small port engine. This is somewhat clouded by the fact that they changed the writing on the cam covers on the large port N/A from blue to red about 3/88 (and the S/C has always been red). (Not to mention that changine the color of a few letters on the cam covers is extremely simple, so unless you KNOW the engine has never been tampered with, you have to disassemble it to be sure what it is.)

It has moved over into somewhat common usages that the '88 and later was a red top. Not really true.

Now, the facts on stronger / more powerful:

'85 / '86 motors had smaller diameter wrist pins and crank journals, and the 3-rib block. All being "weaker" in some respects. In reality, the 3-rib blocka nd crank will handle 170HP easily, and with no problems. It also has a lower rotating / reciprocating mass and lower overall weight - so it's "quicker' to rev and results in a lighter car.

'87 motors were the heavier 7-rib block, but had the earlier crank and wrist pins.

'88 and later motors had the larger crank and wrist pins, as well as the 7-rib block. they also had improved fuel injector dispersion, so they were rated at 3 HP more. They also had slightly milder cams.

The end result is, unless you're going to a boosted or radical racing engine, it makes virtually no difference which one you have.

<edit> There are a LOT of errors on that page you referenced. As well as some good information. For instance - the 212mm clutch became standard in the MR2 in 4/85 (during the '85 model year) not "in some later . . ." as the site indicates. Additionally, the "problem" crank pulley bolts were also superceded mid-year in the '85 model run, and the part # was changed in the parts books so if you bought a replacement you got the newer one. </edit>
 

·
MR2-less
Joined
·
9,855 Posts
Alan said:
short summary of what ITA-MR2 said...

blue top = can handle boost

red top = lighter internals, rev faster
That isn't what Norm said at all.
The internals were the same in the later "blue tops" as they were the "red tops"( larger crank and rod journals) if you go by what he said (blue top being large port, red top being small port).
So why would you say red top internals are lighter?

EDIT: I think you just got it backwards. ;)
 

·
Registered
Joined
·
1,109 Posts
Discussion Starter #8
ok sry to repost something that has been discussed a thousand times... but i couldnt find a post related to it.. guess i just didnt search long enough... but im still trying to learn more motor info....

please dont shoot me ::ducks and covers:: ...... but what is the difference between the large port and small port??? and they are both T-VIS right?
 

·
MR2-less
Joined
·
9,855 Posts
Metalroach said:
. but what is the difference between the large port and small port??? and they are both T-VIS right?
Nope.
Large port has T-VIS, small port doesn't.

The smaller ports elliminate the need for the T-VIS. Smaller ports equals higher air velocity which is what the T-VIS does when the butterflies are closed.
 

·
Administrator
Joined
·
42,296 Posts
The ultimate N/A for the street is a small ported 1983-1986 bottom end. Why? Because you have a better intake manifold and head design combined with the lighter bottom end of the revision one block. You will make more torque in the lower RPMs and in the very important middle. This will make your car much faster. Peak HP numbers are really cool for bragging rights, especially on the internet. But that ubber important middle are of the torque curve will make the AW11, which is fairly heavy, a much faster car in real life.
 

·
Registered
Joined
·
352 Posts
Hmm.. so my question would be.. why would they choose a worse intake etc. for the 87+ models?

For instance I have a late '87 model (NA) with the tvis etc. What Bill is saying if I read him right is that my engine will in fact make less low end torque and mid range power than an 86?? Really? I'm slightly annoyed by that :p What was toyota thinking when they made that change? Surely there must have been a good reason...
 

·
MR2-less
Joined
·
9,855 Posts
GreeBo said:
Hmm.. so my question would be.. why would they choose a worse intake etc. for the 87+ models?

For instance I have a late '87 model (NA) with the tvis etc. What Bill is saying if I read him right is that my engine will in fact make less low end torque and mid range power than an 86?? Really? I'm slightly annoyed by that :p What was toyota thinking when they made that change? Surely there must have been a good reason...
the intake is the same for all large ports (and all MKI MR2's 85-89).
They made the internals bigger for reliability after '87. You know Toyota, always over-engineering everything. :)
 

·
Administrator
Joined
·
42,296 Posts
There was. They needed heavier duty, longer lasting, less noise, smoother operation and something that would take the abuse of a supercharger. So the biger internal block was made. It is cheaper to manufacture a single block than two.

By 1987 the SW20 was already on the design table. The 20v 4AGE was still on the drawing board.
But look at the 20v. Lighter weight internals compared to the SC.

Toyota looks at what is going to make them the most money and what will still keep the car reliable. It has nothing to do with what will make the car the fastest. If so they would have brought over the 20v in at least a FWD corolla.
 

·
Registered
Joined
·
352 Posts
Sigh :p

So whats a set of streetable (but faster) cams going to cost me someday? (LOL I just know it'll happen). Who makes em? (I know Bill knows this one :D )

OH and as an aside, has anyone ever consider an oil scraper? Does one exist for the 4AGE? Would one actually see the benefit? Just something i've heard a few people throwing around..
 

·
Administrator
Joined
·
42,296 Posts
I use a crank scraper. I actually have quite a few of them hanging on the wall in the shop. I keep buying them for some reason.

They were dyno tested by TED Components and proven to not make any more power than stock.

Cams? Streetable? Pass emissions? Gas mileage? == Nothing beats the stock cams for reliablity and for making the car the best for the street.
Now for power on the street then there are many other variables. You have to pick your cams to your vehical and match them to the other mods you may have on your car.
I would contact TED Components and talk with Richard to see what is best for you.
 
G

·
Guest
Joined
·
0 Posts
ITA-MR2 said:
I'm sorry - but this has only been discussed about 1500 times on this very forum.

To make a long story short:

The "true" red-top is the small port engine. This is somewhat clouded by the fact that they changed the writing on the cam covers on the large port N/A from blue to red about 3/88 (and the S/C has always been red). (Not to mention that changine the color of a few letters on the cam covers is extremely simple, so unless you KNOW the engine has never been tampered with, you have to disassemble it to be sure what it is.)

It has moved over into somewhat common usages that the '88 and later was a red top. Not really true.

Now, the facts on stronger / more powerful:

'85 / '86 motors had smaller diameter wrist pins and crank journals, and the 3-rib block. All being "weaker" in some respects. In reality, the 3-rib blocka nd crank will handle 170HP easily, and with no problems. It also has a lower rotating / reciprocating mass and lower overall weight - so it's "quicker' to rev and results in a lighter car.

'87 motors were the heavier 7-rib block, but had the earlier crank and wrist pins.

'88 and later motors had the larger crank and wrist pins, as well as the 7-rib block. they also had improved fuel injector dispersion, so they were rated at 3 HP more. They also had slightly milder cams.

The end result is, unless you're going to a boosted or radical racing engine, it makes virtually no difference which one you have.

<edit> There are a LOT of errors on that page you referenced. As well as some good information. For instance - the 212mm clutch became standard in the MR2 in 4/85 (during the '85 model year) not "in some later . . ." as the site indicates. Additionally, the "problem" crank pulley bolts were also superceded mid-year in the '85 model run, and the part # was changed in the parts books so if you bought a replacement you got the newer one. </edit>

Sorry but they never made a 7 rib with the light internals. I have several early 87 motors that are 7 rib and all of them have the larger internals. Even one of my motors that the car had a production date of early 87

You do not have to dissasemble the engine to know what you have *LOL* a 3 rib block is always the light smaller internals while the 7 rib is always the larger internals.

As for the cams, they have always been 240 degree 7.56 lift cams in all the largports! They did not change to a more mild cam until the small port hi-comp in which they went to 232 degree 7.1 lift cams!


All in all for a built n/a motor you are going to punish, I would only consider a small port with the big bottom machined down. Strengh differences are massive between the old 3 rib and the 7 rib. If you have lower hp goals in mind such as 160 and down then yes, the 3 rib is an option.
 
1 - 20 of 105 Posts
Top