I apologize in advance if this is a noob question, but I searched around for a bit and didn't find a sufficient amount of information on the matter.

There are a handful of options to increase the displacement of the 4B11 and as many of you know, there are 3 ways of doing this: increasing the bore diameter, increasing the stroke or doing a combination for both.

While R&D for the 4B11 has been going on for almost 3 years, I feel there is still little information out there on how good some of these options are and which method is better suited for a predominantly street driven car that sees the track once a month or so.

I'm primarily interested in the 2.2L options, mainly AMS and Cosworth. AMS is a sleeved short block with a 90mm bore and a 86mm stroke while Cosworth is a stroker kit with a 86mm bore and a 94mm stroke.

I know the 4G63 is a closed deck cast-iron engine so upping the bore might be the more practical thing to do on that engine, but may not be the wisest method on the 4B11's semi-closed deck aluminum engine.

At any rate, which displacement method would be ideally suited for an Evo X that's an aggressive daily driver and what would be that advantages and disadvantages in both cases? I'm more or less curious of what the max power potential of both options at the same displacement would be with the same supporting modifications. I would like to hear your experiences and opinions.

Thanks

 

for a dd, stroking is cheaper. if you want to go with a big turbo and need to raise the rev limit to make use of that then maybe a resleeve is better for that application, but its gonna cost you...

 

I would definitely use a bigger turbo with cams and valvetrain. I understand that by using a longer stroke I reduce the maximum safe RPM limit, but do you think with the valvetrain and forged pistons and rods one would be able to maybe maintain the stock redline and be safe?

 

stock redline is very low. if you get a huge turbo, you're gonna need more revs to make use of it. in that case if you have the money, resleeve and overbore is best. i believe the AMS cars use a 2.2L resleeved overbore. its the "best" option but also the most expensive.

if you want to keep things sane, you can get a stock frame turbo like the FP red or black, stroke it, and get stock like spool. these turbos make power past stock redline but with the added displacement, maybe you are happy with the performance under 8k rpm and dont need to rev so high. with a built stroker motor, you can rev past stock redline, but you may be playing with fire as piston speeds go waaaay high on a street car.

 

Thanks for the input everyone, I appreciate it.

The AMS big-bored block and the Cosworth stroker kit are the same in price, which is partly why I'm interested in seeing what you all recommend. It's true, that you're definitely having more extensive work done through the AMS option but sometimes less may be more.

AMS says their kit has 10,000RPM revving capability. Cosworth doesn't say what their max RPM level is, but they do say their rods and pistons are forged and the crankshaft is fully counterweighted for high RPM revving. I'm assuming using MX-1 cams with their ultra-high revving valvetrain combined with the stroker should be able to rev to at least 8,000RPM's depending on the turbo. In all honesty, I think a stock framed turbo (probably the FP Black) would be ideal for me.

Additionally, Buschur Racing mentions on their short-block assembly page that in their last 2 years of testing they feel leaving the cylinders walls alone is the best way to go as they feel the 4B11 hasn't sustained significant bore distortion or cylinder damage even during "ridiculously abusive conditions." Then again, this Buschur Racing short-block is for a built 2.0L.

 

Don't forget to account for the tranny. It may not shift well at 10k. Talk to shep.

Wouldn't you also need a custom clutch for 10k operation? They can explode I think if spun to fast..

 

Exedy has a push style triple metallic HD clutch which AMS uses in their 900X package. It can handle up to 850+ HP and is used in their time attack car.

 

labor definitely wont be the same. if you're baller like that, go AMS.

i personally would get the ERL 2.3L kit and get a stock frame FP red/black and tune it for a broad torque curve. you dont need high boost and high revs on the street. the ability to get instant acceleration without having to downshift... THATS a street car in my book

 

DO BOTH!!!!

Seriously though, as long as the new sleaves areinstalled properly that HAS to be the best option in terms of strength! look at the Honda guys and the LS V8 guys. cast in or press in sleaves are often very weak and prone to cracking. I know the LS guys had alot of problems with the bores not being stright. so when they refreshed an engine some punch a hole in the sleave. With something like an ERL block (these guy do thuis thing day in day out, they know what they are doing!!!) you are getting thicker sleaves that can take ALOT more load!

Stroking a bigger bore engine would be the ultimate!

Chris.

 

It seems ERL has a 2.3L (stock bore with 97mm stroke) or a 2.5L (90mm sleeved bore with a 97mm stroke). That 2.5L would be pretty crazy.

I agree with you madfast, an upped displacement 4B11 with a good stock frame turbo would be ideal for street.

chuntington101, Jun Auto also has a 2.3L that's a combination of both (87mm bore with a 97mm stroke). However, I'm not sure how ERL is able to get 2.3L with a 3mm larger bore and the same stroke as the Jun kit. At any rate, there's somebody going by the name Gump (maybe a forum member here) who's using the Jun kit with several other goodies and putting down 816AWHP and 613AWTQ.

Here's the video on the dyno

 

It's simple math.

Jun stroker kit: pi*(8.7 cm / 2)^2 * 9.7 cm * 4 cylinders = 2307 cm^3(cc) ~= 2.3 L
ERL stroker kit: pi*(9.0 cm / 2)^2 * 9.7 cm * 4 cylinders = 2468 cm^3(cc) ~= 2.5 L

But I see your point - the actual difference in displacement is 161 cc or 0.161 L not 200 cc or 0.2 L as the rounded figures suggest.

 

Thanks UT_EvoX. I never knew the formula used to calculate displacement.

For those interested, I sent an e-mail to Cosworth asking what the maximum safe RPM limit to use on their 2.2L kit with their valvetrain and cams all while using a stock-frame turbo. Here's what they had to say: