Squid4life
Well-Known Member
- Joined
- Jul 5, 2004
Can someone explain why stage II heads are not streetable?
- Thread starter norbs
- Start date
Well...I hope you're ashamed to run those. Obviously they don't work for you. I mean, sh!t, 141 in a daily driver.
I hope you've seen the error of your ways.
Dusty Bradford
Well-Known Member
- Joined
- May 24, 2001
So this combo will be a 231ci engine with a GT42 76mm turbo and shifted at 6,000 rpm with Stage 2 heads?
At least it's a better combination than mine, right?
Yes and no, building 2 motors one 3.8 and 4.1. The 3.8 is the test engine, with out of the box stage 2 heads and the 4.1 with fully ported chapman heads. If the 3.8 nets good results then I can assume the 4.1 will work even better. The cam selection is 230 duration so far.The turbo is a GTXR4202, which outspools a gt42r and flows 10% more than a gt4202. The gt4202 supports 1000BHP and gtxr4202 supports 1150 BHP. All I need is to run a high 9@18psi, good throttle response and I will be happy with everything. If this requires 7000 rpm I;m not sure right now.
Dusty Bradford
Well-Known Member
- Joined
- May 24, 2001
What ci though? Reason I'm asking is concerning the lack of low end torque you will get with these heads.
For example you swap a 231ci combo from a conventional head to a stage 2 head with a 230 cam and it may feel like your converter has been tightened 400 rpm down low, making it lazy. You loosen the converter up to get it to spool then you loose top end efficiency. I would almost expect you to need nitrous to assist spool-up with this combo.
On the other hand, you build a 274ci combo with a 230 cam and turn it 7,000 you could be very happy. The ci gets most of that low end torque back you lost with the head swap and spool-up is very similiar.
Keep in mind a 230 cam on a 231 will pull to over 8,000 rpm.
I'm actually a fan of the larger port heads, they don't bother me. They will in fact make the same hp at lower boost due to the increased head flow. Only issue I see with them is you being disappointed in spool-up with a small engine, large cam, large turbo and stage 2 head.
It will be 232 CI, but i do have the quick spool valve and a ,98 a.r I could use for the street, it might help, I am hoping, but you have a good point.
Camarosnake
Member
- Joined
- Nov 11, 2003
Holy crap Norbert... throw that 3.8 in the back of your garage and put that 4.1 in and you will be able to make all your numbers... can't see that happening otherwise... Putting stage 2 heads on that 3.8 block would be defeating the purpose IMO
Squid4life
Well-Known Member
- Joined
- Jul 5, 2004
Out of the box as in unported? That will make a pretty substantial difference between the two sets of heads. Unported SIIs look almost like naked "as cast" cores. The port difference between the two sets must make a diff in rpm and spoolup I would imagine as well...? Could you assume better than production style heads, but still not as crazy as typical stage heads, as 95% of stage heads I have seen are fully ported.
To answer that question;
It's not that I 'need' such a big turbo. It's what I picked out for my experiment. The idea was to run a turbo in its maximum efficiency zone at max engine loading, while attempting to answer a question I had. "Could the obvious lack of spool up quality associated with using such a large turbo with a small engine be compensated for with the use of nitrous oxide injection? And,... Could a turbo of this size be brought to a launch ready boost level within a reasonable amount of time with the help of the nitrous oxide injection?"
The next question typically is, "Why bother trying to match a turbo to run in its maximum efficiency zone at max engine load?"
The answer to that question has to do with the most primary goal of my Stage I project. Produce a complete supporting system (cam, intake and fueling, exhaust manifolding and turbo) for the heads I chose to use for the project, that would net the best output I could possibly hope for with these heads.
The answers to those questions are the result of the work I bothered to perform on my project. What better way to prove out a theory, right? I mean, we could have all just sat around our computer screens and bench raced about what might be and could have been. Or, some of us could get off our behind and work on some theories to find out for ourselves what is possible and what is not possible.
Heck, if I ever get to a point where I want to go with a smaller turbo, there will most likely be turbos available that will beat out the best of what is presently available. That's just the way technology goes. So, you guys keep trading out turbos as the next best thing comes out on the market, and I'll just sit back and keep doing mid to high 8s with small valve heads using my nitrous and monster turbo and wait for a time when I'm ready to give it up for the latest, greatest turbo to come out on the market.
I respect that some have offered up their opinions, observations and experiences to Norbs, including myself. I can see that Norbs wants to find out for himself what the results of his dreams, hopes and ideas may be. Whether that be bad, acceptable, good or brilliant. I can completely understand that. That is the type of world I live in.
So people. Offer up your opinion, but please don't pile on, or discourage a person from following his dreams.
Norbs. I am going to tell you something that I have learned from experience. If you feel like sharing, that's fine. There's nothing wrong with sharing. But, don't hope for too much support, and hopfully you're not the type of person who needs a lot of support in order for you to pursue your dreams. You just need to buckle down and do it. Let us know how it turns out. I'm pulling for ya.
So people. Offer up your opinion, but please don't pile on, or discourage a person from following his dreams.
Norbs. I am going to tell you something that I have learned from experience. If you feel like sharing, that's fine. There's nothing wrong with sharing. But, don't hope for too much support, and hopfully you're not the type of person who needs a lot of support in order for you to pursue your dreams. You just need to buckle down and do it. Let us know how it turns out. I'm pulling for ya.
Camarosnake
Member
- Joined
- Nov 11, 2003
Just so people know, norbs and I are friends and I am just busting his balls so to speak about his engine, he was the one that has done my tuning to allow my car to be as good as it is and he will most likely be the guy that helps take my daily driver stage 2 buick camaro into the 8's... he has helped me enormously... just sayin! Don't want anyone to think I'm being rude or anything..... And I also appreciate all the replies as well and it has been very informative, so thank you...
Thanks everyone for your support, I just tend to do things different. I'm trying to keep the car drivable. Fred, your car will go 8s no problem even with the smaller turbo, just it will require race fuel and more psi, not to worry, and we still can go bigger (1.44) a/r if your running out of steam.
There's no problem with 2.02" intake valves in a 231 ci motor. It'll be perfectly happy peaking at 6200 rpm - with very short cam duration. i'm guessing around 206* and ~.550" lift - the higher the better. As long as the ports are efficient, the bigger the valve the better. I'd want to see over 310 cfm at .600" valve lift. I wouldn't enlarge the port (at the intake manifold flange) to more than 2.54 in2.
You should be ok on the exhaust side. I believe that modern 2 valve turbo motors should have 70-75% exhaust/intake flow. I would have used a 1.55" exhaust valve. The larger the valve area, the more sensitive the motor will be to proper cam timing and your whole combo.
best of luck!
You should be ok on the exhaust side. I believe that modern 2 valve turbo motors should have 70-75% exhaust/intake flow. I would have used a 1.55" exhaust valve. The larger the valve area, the more sensitive the motor will be to proper cam timing and your whole combo.
best of luck!
norbs, my fresh 274 inch, stage headed engine has a 236--230 cam that dls specked out for me, using 8847 turbo
i havent run it yet, another DLS, speck cam, 242-242 same turbo, was ok. ptc convertor
specked by dusty worked pretty good, im hoping the smaller cam will help spool up faster,
good luck oc,
i havent run it yet, another DLS, speck cam, 242-242 same turbo, was ok. ptc convertor
specked by dusty worked pretty good, im hoping the smaller cam will help spool up faster,
good luck oc,
Your suggesting I go 206 cam cam? I think I will be around the cfm your suggesting without a problem.
