Heat isn't just about pressure ratio.... the pressure ratio could be very low, and still be generating a lot of heat if the compressor is running well to the right side or even beyond the choke line. It's actually easier to run to the far right side of the map at low boost, or pressure ratio. I think with more info we'll find there is more hp in the 475, but it's no doubt going to limit it.

 

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, We can go from there

 

I totally agree. But the other responses weren’t talking about the surge line side of the MAP. With the way they had responded, I assumed they were referring to the choke point.

 

Has it been brought up that maybe your over powering the converter.

On a mild 460 ford my s480 picked up almost 10mph going from 5 to 7 psi.

 

Thanks guys! You gave me lots to look at! I let you know what I find!

 

I don't see a mention of what heads he has. A set of stock rectangle port BBC heads can consume a TON of air. What does the car ET and MPH?

 

Edelbrock performer round port stock.At 5 lbs of boost 7 Flat @ 100 mph 1/8th mile @ 3200 ft elevation.

 

My 4.8 runs 7.0X@10psi with a cast S475 in my 3700 lb Malibu. I'm in agreement with the others, the turbo IS undersized, but it should still run "better" than it is imo.

What gear ratio, tire, and converter?

 

4.10 with m/t 275 pro radial 4500 stall Turbo 400 trans break only 5 passes with new converter and trans

 

As in a 4500 rpm shelf converter, or is it custom built?

 

Custom built

 

That still sounds too loose for a 454 imo. Where are you shifting? How much rpm drop on shifts?

 

6200! Do not know made 2 test passes and stood it on the bumper then had 3 rounds of elimations

 

yeh mine is 3000 converter on motor, has been 100mph to the 1/8 on 7 psi @ 4500lbs. LOL.

converter sounds great for N/A Sounds a bit high for what your doing. However I dont like to judge based on converter stall cuz they are making the converters stall high and be effecient out the back door on good power these days.

Shift point, rpm drop between shifts , engine rpm thru the traps and mph as well as gear and tire diameter will help peeps give advice or your convertor guy info to see if converter is working properly.

 

I found that the ecm was pulling timing and enrichening the fuel a lot so fixing that!

 

cool , keep us up to date. That thing should role out at that weight.

 

I agree. A 3200 car with an aluminum head 454 and I'm going to guess a hyd. roller should run well on motor.

Good find on the timing and fuel changes.

 

HA! I agree completely. I am new to the gasser turbo world, and the little bit I have learned the RPM's large gas V-8 engines turn require HUGE turbos in comparison to diesels! I own a late cummins 6.7 and a BW S465 with a .91 AR is the cat's meow for an all around driver/towing turbo on stock fuel. Lights quickly, and pulls HARD all the way to the blistering 3250 RPM redline. So hearing that a S475 is too small for a given engine makes me giggle a little bit! A S475 works perfect on top of the stock HE351 in a compound configurati0n. WAY fun to drive in a 8000lb truck!

 

Lets slow this down a bit and start looking towards this with a bit of a factually focused approach. Lets say that we're at 15% drive train loss on 400 to the tire, that's 460 at the flywheel. Hack estimate at 46lb/min flow. We then take the 12 PSI number (notice how the map doesn't go down to 1.33, which is okay) and we multiply that by the pressure ratio of 1.81. That's ~835HP or ~83.5lb/min. You're going to be at the very last line past 62% efficient, and probably a bit further off the map at that rate. Now then, taking 460hp*1.4 pressure ratio (~6 PSI) You're flowing ~64.4lb/min. Not even in the ball park. This setup absolutely needs more compressor.

-If I was cheap and looking to bandaid this, I would end up with a race cover. It may get you a bit more
-If I was looking for the mid range option, I'd be looking at the 83mm or bigger. Even that would be sketchy. Look at the second map below.
-Some aftermarket options exist in this frame. I would investigate those. If I couldn't get what I wanted I would give an S500 or equivalent a look if staying with a single.

It's kind of the blessing and curse of a bigger CID, higher HP N/A build; You can get badass pump gas power but you need a metric ton of turbocharger in order to facilitate it happening.

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I have a s475 on a 462 Pontiac and I took back pressure readings at 10 psi and its was reading 16 psi. I have a small cam in the motor and my max shift rpm is 5600. I have been running this combo on the street for 10 years.

While the s475 might not be an all out race match for a 454 there is no way in hell it should be done by 5psi. You have something else going on.