Hey guys I am currently running a 7875 on3 on my sbf 6.0 8.2 deck motor. It does a really good job up to about 12 psi but beyond that gains are minimal and IAT climbs like crazy so I know I'm way out of turbo. I am looking to find a more capable unit but at the same time I'm a little spoiled with it's instant spool.
I know the limitations of the 7875 are due to the .96 housing, the 75mm turbine and the compressor housing size so I'm looking at a VSR billet 80mm with the 1.25 and 88mm turbine as well as the older tech on3 billet 88 with a .96 housing and 83mm turbine.
I am wondering what has the most affect on spool characteristics - turbine wheel size or housing size? The vsr is larger on both than the on3 but I worry about the 88mm compressor vs the 80..

Thoughts? it's a street car that goes to the drag strip on Friday nights for fun.
1969 Mustang. 363" small block/powerglide, 3700 converter, 10.2 compression, AFR 195 heads, cam ground for a turbo but good street manners. 220/220 @.050, .570/.560 lift, 113 LSA.
E85 with mpfi, 2100 cc FID injectors.
It's all built to support 1200 crank hp and making just about 875-900 now but with IAT's around 250*.

 

What about the billet wheel 7875? It should give enough air to get in the 8's and at $550 it's a great price. But at your displacement and converter and E85 you could run an S480 and still have no trouble getting into boost.

 

I'm guessing you're using every bit of the 75mm turbine as well, so I see the billet 80 with the 96/88 turbine as a good upgrade. I don't see the spool being an issue with your setup, and I would personally go T6 as long as you'll be modding the dp, and cold side.

 

Yeah I'm pretty sure the 75mm wheel is maxed out. In top gear I hit a wall at 6100 rpm.but first gear will easily spin to 8000 at full boost.
Do you really think a t4 housing, all else equal, would be hugely limiting? My setup is an extremely tight fit. Even the t4 flange is literally touching my shock tower so going to a t6 would be difficult. I already have a full 4" DP and it's 4" all the way to the tip. Cold side is 3.25" dia from the compressor outlet to the 4" throttle body inlet.

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If the 7875 spools quick and runs out on the top end, then you need more turbo to make top end, or more and better turbo to have both quick spool and more top end. But it seems that you're on a budget using Chinesium turbos - can't have your cake and eat it too lol. I run an S480 on 50 more ^3in thna you and it works fine, but I don't run over 6500. Id say it should work fine if you're spinning 8K.

If you need a T4 frame and can afford : https://www.precisionturbo.net/Stre...and-Race-Turbocharger---PT7675-GT42-Style/280

 

Hugely limiting no, but with the air they move, and process there's a reason they have t6 flanges, and 5" dp's. The general rule for dp's is exducer times 1.25. 88mm x 1.25=110 or just under 4.5" id. That's not to say your T4, and 4" dp won't make hp, but it's not ideal. You'll have no issues spooling a S480 with your converter, compression, cam, and head combo imo. A billet S475 would even be an upgrade from the 7875.

 

I am actually pretty fine with the HP I make now. I only want just a little more but the main issue today is heat. That 7875 goes thermonuclear at 15-17 psi. I am non-intercooled but spray 2000cc's of meth. At 8-10 psi the IAT's stay around 105 but at 13 they are 180 and 17 gets to 275*. I can live at 180 but 275 is ridiculous.
I know if I can keep the temp around 150 with a turbo not working as hard I will pick up a good 100 hp with ease.

 

Well I ended up ordering the VSR 80mm x 88 1.25 AR unit. Should have it Friday.

 

Looking forward to seeing how that lights off with your set up.

 

Me too. It's gonna be a very tight fit. I couldn't find any firm dimensions so I simply decided to do what it takes.

 

Tight fit but I got her in there. This thing is so much bigger than my 7875. #ad
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I know its been a while and you've probably moved on to other things, but I'm curious how this switch worked out for you.

 

It was the best upgrade I could have done. Response was the same, IAT's we're over 100° cooler and it picked up 100 whp at the same boost.
Went from running 6.70's and 6.50's to a best if 5.95 in the 1/8th with a lot left in it.
Now I have done a Barra inline 6 swap and uses the same turbo.

 

That's awesome, great to hear and thanks for coming back here to respond.

Barra huh? Got bored of the SBF stuff?

 

I mean, it's still a Ford.

 

How does the barra compare to the 363?

 

It makes more power.
Up to about 1500 HP it's a lot cheaper to build than the 363.