Most power and torque on stock internals?

[stevecordiner]

What engine to start with depends on what power you want at the end really.

If you want the 300-400 bracket, a rev 3/4 lump is the way to go.

If you are aiming at huge hp figures its all pretty a muchness given the amount of money you need to spend to get there anyway!

The only one I wouldnt start with is a rev 1. (sorry rev 1 guys)

On the unichip / emanage debate - I hope people start to look into the perfect power SMT7 .... it has closed loop wideband O2 control and the abilities to remove the AFM for map sensor on an early car.

[MR2Mania]

The only one I wouldnt start with is a rev 1. (sorry rev 1 guys)

I have to disagree there, mate. There's no major difference between Rev1/2 engines, especially with regards to choosing which one to start a project on. Also, IMHO, the Rev1 chassis is BETTER (I prefer the handling, unlike the panzy journos that kept crashing the early cars. Guerney did a good job with the chassis. But I can understand how this part is down to personal preference, though.

On the unichip / emanage debate - I hope people start to look into the perfect power SMT7 .... it has closed loop wideband O2 control and the abilities to remove the AFM for map sensor on an early car.

I don't know about the latest offerings by Perfect Power, but when I was at Owens, Mark had looked into them and didn't rate them anywhere near as much as the Unichip. In fact, out of all the Piggy Backs, he felt the Unichip was far superior. It's not just about features, and from a tuner's point of view it's whether the device will accurately do what he wants.

[stevecordiner]

I thought the intake ports were larger on the rev 2 than the rev 1? Thats why I was swaying in favour of the rev 2 over the rev 1 engine - as the huge port size is a definite benefit for a very high hp engine.

If the engines are the same, then I'll rephrase my first comment, it doesnt really matter what engine you start with for a very high hp application given the amount of money that will be required to get there

[MR2Mania]

I thought the intake ports were larger on the rev 2 than the rev 1? Thats why I was swaying in favour of the rev 2 over the rev 1 engine - as the huge port size is a definite benefit for a very high hp engine.

If the engines are the same, then I'll rephrase my first comment, it doesnt really matter what engine you start with for a very high hp application given the amount of money that will be required to get there

AFAIK, the Rev1 and Rev2 engines are identical other than MINOR changes (probably for emissions, judging by the difference of some of the vacuum connections).

I'm not sure larger ports is best. This used to be the theory with NA engines, and recently the thinking has changed. For example, an important part in NA tuning is having the right "port to valve diameter ratio". There's a guy that specialises in tuning motorbike engines, and he actually REDUCES the port sizes and gets more power. The requirements for a turbo car car are different (pressurised flow is different to NA flow), so the ratio is different, but ChrisK on the US Board once sneaked some time with a Renault F1 engine and got down to measuring the ports and bits. He then spent a while experimenting with different ratios either side of what the F1 engine had, and eventually came to the conclusion that the F1 engineers had obviously done their reseach well!

Ever wondered why in the US many people are oversizing the inlet valve? This is to correct this ratio!

Incidentally, ISTR the Rev3 has smaller ports to start with.

[stevecordiner]

Yup, the 1mm oversized valves gives the large port 3SGTE engines a virtually perfect valve / port ratio (is that the valve throat ratio btw always get muddle with the terminology?)

The rev 3 ports were smaller for better velocity since they didnt have the TVIS system IIRC

[MR2Mania]

Yup, the 1mm oversized valves gives the large port 3SGTE engines a virtually perfect valve / port ratio (is that the valve throat ratio btw always get muddle with the terminology?)

Yep, that's it, although I'm not sure it makes it "perfect", just better (you can't go any bigger than 1mm oversize, anyway).

The rev 3 ports were smaller for better velocity since they didnt have the TVIS system IIRC

Yep, and I'm assuming that it worked so that's why they ditched the TVIS.

[stevecordiner]

Do you know if anyone has done any flow bench tests on the rev 3 intake manifold?

I found the results of the rev 2 manifold and it was pretty scary lol. An extra 10-13% more airflow to the middle 2 cylinders compared to the outside 2. The rev 3 one although having a larger throttle body, plenum and different runner size has a simlar design - just wondered if anyone has looked at its flow characteristics, particularly for high boost applications?

[MR2Mania]

Do you know if anyone has done any flow bench tests on the rev 3 intake manifold?

Funny you should mention that, but I had mine done, albeit with the manifold and head together, before and after headwork. The chap doing it said the head flowed very well as standard!

I found the results of the rev 2 manifold and it was pretty scary lol. An extra 10-13% more airflow to the middle 2 cylinders compared to the outside 2. The rev 3 one although having a larger throttle body, plenum and different runner size has a simlar design - just wondered if anyone has looked at its flow characteristics, particularly for high boost applications?

How was your testing done? You have to be very careful about these things. You can't just consider the manifold on its own, you need the head there too. Also, ideally the system needs to be pressurised. It's not the same thing tuning for NAs and turbos. The flow is different.

I personally don't think that there'll be a big differential in realworld flow between all the cylinders. Call me a sceptic!

[stevecordiner]

I have a feeling the testing was done by this lot http://www.extrudehone.com/oem.html but I'm not sure what their procedures were. Quite a few of the yanks have extrude and honed intake manifolds which increase and equalise the flow of the stock one.

Before / After
>#1 246 / 304
>#2 268 / 313
>#3 259 / 313
>#4 241 / 304

[MR2Mania]

I have a feeling the testing was done by this lot http://www.extrudehone.com/oem.html but I'm not sure what their procedures were. Quite a few of the yanks have extrude and honed intake manifolds which increase and equalise the flow of the stock one.

Before / After
>#1 246 / 304
>#2 268 / 313
>#3 259 / 313
>#4 241 / 304

OK, but what happens if the manifold has had all it's runners equalised, but the head remains the same, and then you find that the ports of the 2 inner combustion chambers don't flow as well as the outer ones?

It should all be treated as a system if you're going to get the job done properly.

[stevecordiner]

A good point! I know the plugs often show that the middle two are a little leaner than the outside as well.

I dunno, I'm ditching mine anyhoo

[Bender Unit]

>>Do you know if anyone has done any flow bench tests on the rev 3 intake manifold?<<

Haven’t done any tests like that but I have done numerous plug checks on the car after running 125bhp jets to confirm an equal spread of nitrous among the 4 cylinders and all 4 were identical, which would lead me to believe that the rev 3 head is actually very good equally supplying air to all 4 cylinders.

If there were any issues they would have been very apparent!

Cheers

James

[JJ]

The Rev3 blocks have a weakness, full stop. Some break, some don't. As with anything, there are many variables.

I'll second that, the variables bit ! I primarily blame heat then ignition timing / knock affecting the harmonics during combustion ... look at it like a high pitched frequency cracking glass !!

Most of the cracked blocks have a common factor and thats using the Ct series flame throwers !!

Again, more variables include coolant around the liners, is the engine experiencing hot spots / air in the system ... could we be looking in the wrong place, is the liner cracking from the coolant side... possibly gas passing the HG will only pressurise the coolant system furthermore = hotspots = increased pressures.

Yes I agree using the later thickwalled blocks is the way forward as there is room for error without block splitting. I've bitten the bullet and gone down the route of rebuilding an early rev 3 block I know fine well of the issues around the early rev 3 block, but neither stock ecu is being used ( crazy ignition maps ! ) and the turbo I'm using should be pushing air conditioned air in comparision ... so in cylinder pressures should be reduced and any sort of further tuning will be considered at the upmost caution.

I like to see me testing the waters ... not to come back and say... look, it wasn't a problem like everyone said, but for it to be able to satisfy my own needs and being able to cope for what i'll throw at it... not being die hard serious 2+ bar with it - just sensible.



This is what I'm saying now. Lets see what I'm saying this time next year !

" That damn blocks cracked open at a mere 1 bar and now my pistons, crank, bearings are all knackered... looking for a 98+ block ! "

[MR2Mania]

JJ, I like your thinking mate, but I think the problem is simply that the block is too thin in that area (the blocks are cast slightly on the p!ss, so on the opposite side of the same cylinder, it's a lot thicker) and the thin wall can only handle so much cylinder pressure.

By overboring even slightly, you'll just crack it sooner, I reckon.

But as you say, I'd love it if you could prove that wrong, as that would then open up the opportunity for the Rev3's tuning potential. Go for it mate!

[Bender Unit]

>>I've bitten the bullet and gone down the route of rebuilding an early rev 3 block <<

You’re not the only one mate!

[Bender Unit]

>>JJ, I like your thinking mate, but I think the problem is simply that the block is too thin in that area (the blocks are cast slightly on the p!ss, so on the opposite side of the same cylinder, it's a lot thicker) and the thin wall can only handle so much cylinder pressure.<<

Thing is way back when my car was operational I was running 18psi and 125bhp of nitrous which would create a significant amount of in cylinder pressure and the block coped fine, fingers crossed it will stay that way. With the nitrous activated the pressures exacted on the block would have been very high, also coupled with the fact that the stock CT20b just couldn’t flow that much gas so I would have assumed there would have been significant back pressure as well – or am I talking plops?

Regards

James

[MR2Mania]

Thing is way back when my car was operational I was running 18psi and 125bhp of nitrous which would create a significant amount of in cylinder pressure and the block coped fine, fingers crossed it will stay that way. With the nitrous activated the pressures exacted on the block would have been very high, also coupled with the fact that the stock CT20b just couldn’t flow that much gas so I would have assumed there would have been significant back pressure as well – or am I talking plops?

Regards

James

No, you're not talking plop, mate. NOS *does* increase cylinder pressures. But with regards to being back pressure because of the turbo, this won't affect the cylinder pressures (which are greatest on the compression stroke when on high boost), they simply create back pressure in the turbine housing and maybe in the exhaust manifold.

As I've said before, some blocks seem to last, others don't. It just seems to be luck of the draw.

[TBDevelopments]

Might have missed this as i've just skipped through the thread.

But does anyone have engine and chassis numbers of the rev 3's that were fitted with the weaker thin wall block so we can all check for sure if ours have it or not?

Tim
xxxx

[Mikejc]

From what I can gather it's unknown exactly which of the earlier Rev 3's had the weaker blocks. This is due to the fact that Toyota never officially admitted their was infact a problem!

Mikejc

[JJ]

Part no. for the block changed in 96 ! So anything in between 93 and 96 !!

Be nice if we had access to the original engine department / data details ... obviously the engine numbers are incrimented to builds, so the change will have been along the line as a revision.