Alright guys, i bought this motor setup already. New to V8 motors as i am gonna swap this into an RX7. Mostly for street and autox. Heres the specs.
- Aluminum Gm racing heads: Intake port 250cc, exhaust port is 95cc and combustion chamber volume is 44 cc. Intake valve size is 2.180inches and exhaust valve size is 1.625inches.
- MTI T1 cam: 559 559 intake and exhaust, 114 lobe sep, advanced 4 degrees.

I was told by a friend this setup won't work. He said the intake ports are too big on the heads. I need advice. With this setup what kind of power can i expect? RWHP and torque. Im learning and kind of worried that he's right. I'm already thinking i will have to get some new heads. I got a good price on the complete motor. So advice would be appreciated.

 

No feedback?

 

Your posting on a Sunday morning and expect to get the gear heads out of bed to reply...

I am assuming this is a LS1 bottom end? Dart makes some 250cc heads, but needs a 4.0 inch larger bore. So your answer would be no it will not work.

Sell those and pick up some new ones, you can find 243 heads for cheap these days.

 

Yea, its a ls6. Thanks for the reply. Would it just run like **** and make low power? Just need some logical reasoning. Im learning.

 

I would imagine that those heads are for a 4" and larger bore and will not work on a LS1/6 b/c the exhaust valve will hit the cylinder wall.

If you already have them, sell them and buy 243's like what came on that LS6 motor from the factory. If you have the money, getting them milled and ported would be nice for flow and compression will really help the torque and mid range punch which will be nice for auto x.

 

I'm not sure. I'm looking to make 450-500 rwhp and around the same torque. Mostly for street and autox and the occassional track days. Also something with a mild lope. So what head/cam setup would work?

 

getting that much hp out of stock cube with that MTI cam really doesn't look too good. i'd strongly recommend following this thread

https://ls1tech.com/forums/generatio...heads-cam.html

Patrick G, the LS1 Godfather, explains throughly what you would need to make 500 rwhp on stock cubes. i strongly recommend reading up a bit more and educating yourself so that way you can ask more detailed questions. =D

 

Thanks for the link. But with my setup now, what kind of numbers could i expect?

 

Well what is your setup now, I mean you have heads that wont work with the bottom end.

What supporting mods do you have.. intake, headers.. etc...

You will be hard pressed making that power, just take a look at my setup.. I am pushing 411 rwhp and am pretty much stuck with what I have without spending some serious money and modding the bottom end.

But 400 hp in a RX7 would be pretty crazy anyway. Your not going to make and crazy power on stock bottom end with just a cam and heads. Maybe 350-370 at most.

 

what are the casting numbers on the block and heads so we know what you are working with.way more infor needed.

 

I'm going to go out on a limb here and assume this is your pn# on the heads: 12480090


If so you have a set of C5r heads.

 

Supporting mods include: Intake, 1 3/4" long tube headers, 3" exhaust. Thats basically it. Ideally, low 400rwhp would be nice for now. The car weighs approx 2850. I think i'll finish project and see what kind of numbers i can pull on a good tune and dyno. Then next year do a different head/cam combo. BTW the part # on the heads are 88958622. Heres a link to basically the heads i have:

http://www.superchevyperformance.com...p/88958622.htm

 

Oh, yea have the smaller bore heads so your fine.

That cam is on the weak side and looks to be an older grind which will keep the power down. Your going to need around a 236-238+ @ .050 to make that power with the heads you have and your going to need atleast a FAST 90 to make that thing run.

The details in your first post about the heads dont match the specs in that link, FWIW.

 

Well, i just talked to the guy who sold me the motor. The description of the cam written on paper is different from what he is telling me. So he says it is a comp cam with a custom grind. Part #54-000-11, 559 559 intake and exhaust, 221 221 .50, 110 centerline advanced 2 degrees. I'm getting conflicting specs on the heads. I have a printout from GMperformance that differs from the site i posted. What is actually casted on the head is "LPL LS6-163 88958622. Also the casting on the corner of the block says 243.

 

Well I was thinking C5r heads because those valves you listed originally are ginormous. Other than that it seems like an LS6 head.
That 221/221 cam is sort of a weiner cam and looks like a pretty dated grind.

 

Yea the setup is 4 to 5 years old. We'll see what numbers i make on a good tune and dyno. Its going into an RX7 that weighs roughly 2850lbs. If i make low 400s, i'd be happy with that this year. And next year it'll be a different setup.