Power estimates TwinScrew charged 8.9:1 3V

[Razorbed]

Hi everybody

I`m currently having a 3V block at the machining shop and my funds ready to buy internals.
My goal is 550rwhp and matching torque with my Saleen VI supercharger and a max of 15psi, better if lower.

The bores are allready too worn for the famous Saleen/CP piston solution,
so I have to look out for a new choice.

Mahle +16cc dish result in 8.9 compression. I like the thought of tight ptw clearances and stock like behaviour, but I`m worried that the low compression with have more drawbacks than benefits on my setup.
The Roush 540 hammer and P51 seem to have these pistons too.

My intake and exhaust is completely stock FYI.

Please chime in on your thoughts if that power goal is doable like this.

PS: DSS have some uncoated 4032`s too with 9.3 compression, but their reputation is not that great.

 

[Mystickeith50]

My uncle has a roush 540. At 15 lbs with a jlt, long tubes and full exhaust he made like 520rwhp and 550 ft lb of torque on a mustang dyno. He then added dual bap 2 more lbs of boost and cams and made like 590rwhp. Just to give u an idea.

 

[skwerl]

The low compression will hurt you. These mod motors love compression. I'm about 10-1 and making 640 with 15 lbs of boost. A lot of that is in the heads and cams though.

I would go with no more than 6cc dish.

 

[dysan]

With boost I would recommend the Manley 2618 pistons. Manley likes a tighter PTW clearance and I just started up my new engine which is .020 over bore, 3.75 stroke crank and Manley flat top pistons and there is zero piston noise at cold start-up.

I agree with the others that you really shouldn't go any lower than stock compression. You can still make the power you want with less boost which will in turn lower your air intake temps.

 

[Razorbed]

The Manley 2618 with +6.5cc dish would make near 10:1 compression.

So you are at 640 at the crank or at the wheels skwerl?

Thanks on the recommendation dysan! Did you go with the suggested 0.003 ptw clearance?

 

[skwerl]

At the wheels, of course. Crank hp doesn't count except for new car sales brochures.

 

[Razorbed]

Good point But you have the 302ci with cams headers and stuff...hard to compare.

What would be a realistic hp/tq goal with my minimalistic mods and 8.9 compression on 15PSI?

 

[dysan]

Thanks on the recommendation dysan! Did you go with the suggested 0.003 ptw clearance?

I believe my builder had the machine shop set them around .0035.

 

[MexGT]

There is nothing wrong with 8.9:1 CR for your goals, infact i'd do it to be in the safe side, but I bet you must have high octane gas in your country, thats another +.

I have 9.0:1 on a stroker engine, with 3.73 gears it doesnt feel like a turd before boost like most of the people think it would be.

03-04 Termis and GT500's have aprox 8.5:1 CR.

 

[Razorbed]

The octane here is 95 or 98, but to compare it to yours, you have to subtract around 5 for each.
I`d like to be on the safe side because the gas varies once you travel around like Italy or southeastern Europe.

Any power estimates for that CR and a max of 15PSI on stock intake/heads/cams/exhaust?

 

[TexasBlownV8]

The higher octane will help you. Regardless what the real number is, it'll put a big smile on your face! You'll probably be in the 520-550 range. Worry more about setting up everything properly. A dyno number is just a benchmark; don't fret over a specific target or the numbers or you may not be happy, even though it'd be a blast to drive.

 

[Razorbed]

Good point too.

Just found out that a Roush P-51 makes 510/510 with 15PSI.
But the CR is lower like 8.6

...

I guess I`d be happy with these numbers, as I allready have them now but without the piece of mind that a forged bottom end provides...

 

[Department Of Boost]

My goal is 550rwhp and matching torque with my Saleen VI supercharger

That's easy, even with 8.9:1.

and a max of 15psi

Why? You can run in the 19-20psi range on your pump fuel (not that a Saleen will ever make that much boost).

 

[Sactown]

When I was running the Saleen SC on my car I put down 550rwhp and 510rwtq at about 14psi mods at the time:
Ford racing Aluminator for super charged applications
Ford racing Stage II heads.
LT's, no cats, h-pipe, stock mufflers
127350 comp cams from Brenspeed
Ford racing throttle body
ID1000 injectors
JLT Series 3 CAI
New MAF, can't remember which one, but I think it is the same as on the ford lightening trucks
5 gallon trunk mount ice box

 

[RED09GT]

You can gain a bit of compression back by shaving a bit off the deck if need be-set it to 0.004" and it should be over 9.0:1
As much as it is nice to have higher compression, it won't make it feel like a 4 cylinder by dropping it down to 8.9:1 and it has proven to be a reliable setup.

 

[Razorbed]

No more worries since I grabbed a set of the discontinued 3V Mahle flat tops.