High compression/low boost

[HiPlains]

I'm having my short block completely rebuilt, forged internals, ported heads by Fox Lake - 97 cobra with Vortech T Trim. I'm leaning toward running higher compression (10:1), lower boost (12 psi). My tuner recommends no higher boost levels on 93 octane. Any higher boost requires race gas, which i'm not prepared to do.

Appreciate any input from Vortech guys out there....

 

[milktasd2]

I'm doing the same thing as you but I'm adding cams which should help with running more boost. Don't know what boost level I'll be at. I'll have s. If intercooler and big headers to help lower the psi while keeping power up. Though it's not done yet, so no real world experience.

 

[SpittingCobra]

Factory 9.85:1 compression ratio with flat top pistons, ported heads, D1sc, longtubes, etc. The gauge only shows like 8-10psi at sea level. After all the engine work porting, headers, the restriction is less, you may find the blower doesn't hit the "psi" number that you expect anyway. You can run methanol injection as a solution as well.

 

[HiPlains]

I'm doing the same thing as you but I'm adding cams which should help with running more boost. Don't know what boost level I'll be at. I'll have s. If intercooler and big headers to help lower the psi while keeping power up. Though it's not done yet, so no real world experience.

I'm adding Cams, too. Will talk to my tuner ....can't wait to get this on the dyno.

 

[HiPlains]

Out of curiousity, if I ran smaller pulley and race gas/meth, what kind of rwhp and boost levels have been experienced ? I'm interested in seeing what the upper limits are on these motors.

 

[HiPlains]

I'm considering a pulley swap ...run maybe 16, 18, 20 psi ?? Also, looking at the meth kits from Snow Performance. My math is coming up like this:

Actual rwhp BEFORE pulley swap/meth/Fox Lake heads - 568rwhp
x 1.20 increase with swap/meth (as per Snow Perf on FI applications) = 681rwhp/.85 = 801 crank hp

These numbers are crazy. I realize that this does not take into account the new heads and the last dyno was several years ago. I'm just trying to set some realistic goals before hitting the dyno.

 

[milktasd2]

I'm gonna run a 3.0 and 10% overdrive and I'll be overspinning the blower a little at 7k. Psi is just a measure of restriction. What's 12psi on one build might be 20psi on another, but both are pullied for max blower rpm. Basically need a bigger blower if what you have isn't enough. I was trying to find some one to trade for a JT blower plus cash, because I think the t trim won't quite be enough and I don't want to jump to the ysi.

 

[96S/Cobra]

It sounds as we will have a similar combo, so I can give you some real world knowledge as far as my stats and what has worked for me.

My combo:
8.8:1 w/forged internals
SHM blower cams
T-trim w/2.85 pulley (makes 20 psi.)
10% OD crank pulley
Long tubes w/off road mid pipe
Meth Injection
93 octane
13* of total timing
~600 rwhp (598.XX I believe)

What I don't have that you will is ported heads and a 10:1 cr. How much boost you can safely run on 93 with a 10:1 engine is ultimately up to the tuner and how aggressive they want to be (or not be) with the tune.

The total timing on my car is ULTRA low, so the tune is very conservative to say the least. Keep in mind that every tuner is different. How conservative or aggressive they get with the tune will vary greatly, thus resulting in a wide range of rwhp expectations. But I would think a realistic expectation for a 10:1 engine w/12 psi would be 560-590 rwhp. I believe there is another member on here who had a somewhat similar combo as yours and mine and I believe he was at approximately 630 rwhp. That goes to show you that slightly different pulley and cr combos/dyno's/tuners/total timing will net similar yet slightly varied results.

Also remember that every dyno is different. You may have a specific number in mind as far as a realistic expectation for your rwhp, but as long as it is tuned SAFE and runs great, what more can you really ask for?

 

[Helomech74]

I'm running a 17psi of boost at 6300 rpm with a procharger F1A and making 753hp/667tq with 10.3:1 compression on 93 octane/22 degrees of timing and no issues at all. I'm running Crower cams (62824's), so dynamic compression is a bit lower.