I would like to add a procharger (p1 or D1 sc?) to my 383 tpi. Right now the motor has approximatly an 11.1:1 compression ratio. If I switched the heads with ones with 10cc bigger chambers, and used an inter cooler, around how many pounds of boost would I be able to safely run using 93 octane fuel as well? Modifications are in my sig. What size injectors would I need to use (current 30lbs probably aren't enough). Would the stock ECM be fine or would I have to switch to an aftermarket set up? Thanks

 

Get the D...blower...

 

im in the same boat as you. im running a 383 w/ stealth ram at 10.8:1. would love to go with a pro charge if its worth it

 

if i remember right i went from 13.1 to 10.8:1 by going from a 64cc chamber to a 75cc, your can also run thicker head gasket to lower compression

 

I run 8lbs of boost with 9:1 compression, but I've been having all sorts of ring sealing issues so don't take my words of advice!

 

Guy here awhile back dropped compression down buy switching head cc's and i believe he ran over 10 psi with no issue on near 10 to 1 with aluminum heads. I dont doubt it, i ran 18 on 9 to 1 so chamber pressure should be similar.

Go D1 and intercool. If you are at 9.8 to 1 with a 75-76 cc head and use a cold plug and careful tuning, it will be fine.

Id run 60 lb injectors if you are looking for 10 psi or so with afr 195 heads or similar on that setup. Its gonna make serious power. Stock ecm like 730 map based running a boost code like $59 should be fine. Or EBL i believe. Else need aftermarket. I wouldnt do fmu on that setup.
Also get a walbro 255 pump and hotwire kit to alternator for more volts. Needed for 550+ whp

 

The FMU doesn't concern me due to the fact that it's a static ratio, but because of the high fuel pressures one would encounter, and the pump required to provide volume at those pressures.

No FMU.

-- Joe

 

Yeah the pressures is my concern with a single pump. I am not sure what ratio is needed, 2 to 1, 6 to 1? 10 to 1? 12 to 1? If you ran 10 psi and made 500-550 whp lets say, your fuel pressure would be 43 base plus 20 psi for 2 to 1, and upwards of 160 psi at 12 to 1! No way a walbro or the injectors would function at that high level. Under 75 psi it should be ok but hp limit is reduced. May not support 500 whp at 75+ psi.
Now i think between 2-4 to 1 rate would work for a V8. 500 whp needs 42 lbs inj minimum. I just suggest 60's for room and they may be had used more often and also sometimes cheaper than smaller injectors. Siemens ones are nice

 

So if I am at approximatly 11.1:1 compression and I go with the 75cc AFR over my 64cc AFR's now and run the same head gasket size, what type of drop in compression should I see? Is that 730 map ecm a speed density set up? How would it run with a tuned maf set up?

 

When i had my 11 to 1 383 with 64 cc an going boosted i was gonna sell my afr's for 75cc 210 heads and that with same gasket keeping .040" quench would give me 9.8 to 1. Plenty low for under 10 psi and it would make strong power with right cam and intake....

But things spiralled out of control and i built a low comp dart block 400

 

The sweet spot for E85 is 11.1:1, just something to consider as an option...

 

I wish I could get that around here...

-- Joe

 

I would be keeping my ported aftermarket tpi set up and current cam as well. So with the swap to the 75cc heads I should be good with 8 or 10 pounds of boost? Also, would it run better with AFR 195's or something bigger such as the 210's?

 

Those heads are pretty close. Blower overcomes larger heads and i feel a higher reving 383 would love a good 210 cc head but with tpi's shorter rpm range run the 195's

I was up around 800 hp with afr 195's on 15 psi on a 400

 

I'm wondering what your ring gaps are set at??

 

Sould I go with the competition port that they offer as an upgrade? I'm not sure what the ring gap is set at.

 

I am surprised nobody mentioned twin walbro in-tank fuel pumps.
On a 700rwhp setup, you can have one pump run all the time, and the second pump come on at a set boost pressure. That will keep the unnecessary heating of the fuel to a minimum, as well as current use.

As to the compression dilemma, If you are seriously considering a false atmosphere build in excess of 13psi or 600rwhp, that will usually cost a couple thousand dollars to do right, you should also seriously consider a lower compression piston. If that is not an option, then get a large combustion chamber head, and consider water/methanol injection as your alternative. Get the compression as low as you can, do whatever it takes. Because even at 8.5:1 or even 8:1 compression, with 93 octane a 5.7L engine around 18psi can produce well over 800 horsepower.

 

One other thing to think about is how you are going to retard your timing under boost...not unless there is a way to do it through your computer, I run a carb set up so bought a boost reference MSD box that currently pulls 1 degree or timing out for every 1 pound of boost. I can change that to pully 2 degress for every one pound or even 3 degress for every one pound if some one was making insane boost.

 

I am planning on using one of those MSD boxes as well. I am going to be switching to a larger cc head to get the compression down to around 9.5:1. I only plan on running approximatly 8 to 10 lbs of boost while using 93 octane fuel. So what would be a good fuel pump to swap in place of the stock in tank one?

 

As far as replacing the stock fuel pump I went a different route, I decided to go with a billet aluminum aftermarket tank that has the pump mounted inside the tank. With running bigger pump I needed to run bigger fuel lines, the stock fuel lines were to small and would not flow enough fuel quick enough for my application, I went with -10AN supply and -10AN return for the fuel lines, Chris with Behind Bars Races Cars was good to deal with.

http://www.behindbarsracecars.com/Al...p/bbrccpit.htm

The pump in the tank I went with is a magna fuel pro tuner 525 pump, which is good for 1000hp.

http://www.summitracing.com/parts/MRF-MP4302/

 

Single walbro with a boost a pump setup could likely do 600 whp. You may approach 550-600 with 10 psi so it be sketchy. Duals would be nice but pricey unless you build yourself. I am curious to see if the 340 lph pumps out there can support the high hp numbers. That be a nice option. Talk to LonnieP on this forum. He did my fuel system

 

I see a lot of intercooler choices as well such as 2 and 3 core models. Which would be bettrer for my application, and will there be any fitment issues with either model?

 

I went with the cheap ebay intercooler most people use. The whole kit is a couple bucks, and fit's a thirdgen with some minor surgery.

https://www.thirdgen.org/forums/memb...ught-home.html

Post 18 onward.



-- Joe

 

I went with the 3-core from procharger...didnt exactly fit like a glove, but I got it to work.