Thats what this forum is for. I still can't believe a thread has made it to the second page without people arguing with each other yet

 

Alberto is sleeved, but .020 overbore...still a 3.5L.

His build was done almost a year and half ago. I lot has changed since then.....and most shops are comfortable pushing much much further without sleeves.

 

awesome thread! great info from all angles!

 

Sharif, your car is a sleeved 3.8L correct? Is there any way you could overlay the dyno charts from your 3.8L sleeved setup and a similarly prepped 3.5L setup? I am curious though as to why Alberto decided to stick with regular 3.5L sleeves instead of boring them out like yours.

 

Very helpful, I've actually been thinking about the exact same thing in a not so technical sense! Glad to see all the different views and details about these types of builds.

 

All of my 3.8L runs were on the other dyno, so I don't have those files anymore.

However, I saw maybe a 5-7% power improvment over the 3.5L. It wasnt a huge difference, when compared to the 3.5L engines we have tuned.

 

So in terms of peak power, there wasn't a huge improvement. What I am really curious about is if the turbos spooled up any quicker and the difference in powerband compared to a car with stock displacement. Then again, I might be overestimating the effect of the extra displacement a bored-out, sleeved motor has.

 

Oops-forgot I Was 0.020 over standard overbore, no noticable difference.

FWIW-Sharifs car with 3.8L 20G's and 19.5psi = 652whp, jkenefic with a 3.5L, 18G-standard Greddy snails and meth at 19psi = 650whp. Its a wash, there is roughly a 20-30% surface area reduction on the headgasket with a 3.8L thats been bored out, I decided against that because I wanted to run an HKS headgasket over the Cosworth. I can EASILY make up a 50 or even 100whp difference in driving against most people, so a few whp at the "sacrifice" of reliability wasnt worth it to me...

 

lol, what is your secret exactly with the driving thing?

 

Hard to explain you just have to see it.

I have always been critical of my driving since the summer I turned 16 and started driving/drag racing. I LIVED at the dragstrip that first summer I found it lol...

 

Here is a link to our short block on our temp server,

Stage 2 Sleeved Short block:
http://gtmotorsports.test.gatesix.co...cat=475&page=1


Stage 3 Hi-Rev 3.8L Stroker Short Block:
http://gtmotorsports.test.gatesix.co...cat=475&page=1

Like I said, less than a couple of hundred dollars price difference.

-George
GT Motorsports

 

Well, thanks for the info Alberto and George. Like I said, unfortunately I don't have the coin to build/stroke/sleeve right now, but this thread still has some great info in it. Hopefully by the time I do have the cash, I'll have driven in and ridden in a variety of setups.

 

BTW-where in Clemson are you I have a friend there and I stop to see him when Im anywhere down there....

 

I am as "in" Clemson as one could possibly be. I'm somewhat embarrassed to say this on a public forum, but unfortunately I live in dorm in the center of campus,lol. Anyways, for sure hit me up next time you're in the area. BTW, does your friend go to the university?

 

Yeah he is in grad school, he has a silver Subie 2.5RS (lowered/exhaust) you may have seen him around.

 

I think you guys are assuming a 3.8L bored out engine is the same as a 3.8L stroked engine, it is not. When you have a stroked engine, the piston travel speed is increased creating a higher amount of exhaust gases coming out of the engine. This will create, in a turbo car, a much more responsive and "torquey" engine. The turbos will be spooled faster, hence making more power down low.

As an example I would like to share this dyno graph of our 3.8L stroker engine coupled with a APS Twin Turbo system, running only 10psi. Show me a 3.8L sleeved engine with 100mm bore making 500rwhp at only 10 psi with a APS kit (this is not a extreme kit btw)



So this shows that if your budget allows, a stroker engine would be the best avenue to take for your build, also in the high performance realm there is no such thing as over building, the stronger you make an engine the longer it will last and more efficient it will be.

Do you want to make 650rwhp on a dyno one day? or do you want to put down that power every day? That will also determine which approach you should take for your build.

Good luck!

-George
GT Motorsports

 

Yeah, I've seen that guy around (i think). We have a good bit of wrx's, sti's, and evo's running around down here, but hardly any Z's. The big thing here in Clemson is pickup trucks with all the wannabe good ol' boys.

 

You gotta watch out for those turbo diesels

 

Very true. Thanks for the graph George. Those are some seriously impressive numbers for a ST car. I'm presuming no C16, meth, watet, etc.

 

99% of the guys with trucks around here couldn't care less about performance. However, diesel trucks can be nasty out of the hole. From a roll though, they don't stand a chance.