Looking to do a 4.8/th400/3.27 in a Mustang and wondering what would be a good turbo for overall performance in terms of response and max power. I would go with the s475 but I think the same performance can be had with a physically smaller turbo. Would the TC76 or 78 with the 68mm turbine still limit performance on this smaller engine? I like the PT76/75 but its a little pricey. I will likely stick with a brand name turbo. Thanks

 

7675 would be pretty rowdy, but they are big money. I would stay away from the small turbine.

 

Shoot us a power goal and we can guess at what turbo would be most responsive to make that goal. Also would need some detail on the 4.8. Compression? Fuel? Cam? Intake? Etc… They will all spool the same turbo at different rates IMO.

 

As much power as I can get w/o the power band mimicking a 2-stroke dirt bike lol!

Probably going to be a Gen IV, stock except for valvetrain (smallish cam). I will be running 93 octane on the street and will use race fuel for track day.

I like the s475/t6/1.32 but the dam 5" down pipe make for packing difficulties.

 

I’m doing something similar this year so I’ve researched it a bit. This is just my take on it… feel free to disagree!

Look at the 4.8 record holder running the S484 T6 (mxguy1286). I’m sure he doesn’t consider the power band “dirt bike like”. But you can’t expect something for nothing. Smaller engine has to rev more to make the same power. No way around it if you want an efficient setup. Turbos love RPM as well so that’s not really a bad thing.

You need a “loose” converter that’s capable. mxguy1286 ran the 9.5 PTC with the 17 stator shifting at 7200. He also ran a 2.5" hotside (which is leaving some spool time on the table IMO). Slap a nice 2", 2.125, 2.25" hotside on that T6 S475 and it will perform great. Better than the precision unit for MUCH less $ I’d bet. (If you take advantage of the lower back pressure the S475 provides.)

IMO you don’t need the 5” DP either. Keep the DP short without many bends and neck it down to a 4”. Cut the goofy 5” flange off and weld on a 4” Vband. (or get the LJMS 4” adapter) Figure the “96mm” wheel has an 87mm exducer. 120% of the exducer wheel DP sizing rule puts you right around 104mm or 4” for the DP. I just did this on the VS S480. Really wasn’t too hard to weld up a 4” Vband flange on it. More pics and details in the rx7 build thread.



I wouldn’t limit yourself to stock intakes or smallish cams either. If the budget allows it and you really want the 4.8 to shine, it needs to have the supporting parts to make good power from 5500-7800+ IMO. Kinda what a destroked engine is meant to do. More HP you make over peak torque the better. If you go with the larger T6 turbo housing you’ll have less overall back pressure which will allow for a larger cam and more RPM.

I couldn’t do all that I wanted converter and intake wise with my budget so I had to make due and pick a cam that suited the parts I was running. If you really want it to run well build it similar to mx1286’s setup.

https://ls1tech.com/forums/forced-in...6mm-notch.html

 

I would buy this

https://ls1tech.com/forums/parts-cla...let-wheel.html

 

My son has a S475 with a 5"to 4" reducer right off of the turbo. It spools nice and I wish I could give you some feedback on the ON3 84/75 I just put on my car. Slowsedan went pretty good with it...Like 137 with a slipping clutch.

 

Thanks Adam. I hear you on the fact that the 4.8 will need some rpms. I was planning on a "loose" converter from PTC or Trans Specialties down the street from here. The loose converter helps with spool and I think keeps these engines alive lol! I think the 216 TFS cam would be about perfect for what I'm doing. I am considering the s475 again as its been a reliable turbo for me but again the sucker is huge and makes for a difficult install for the way I want it laid out in the car. The 5" inlet is also a PIA . I would opt for the T4 option so I wouldnt have to weld on a 4" adapter...my luck I'd botch that and be out the 200.00 to replace the housing. I was just wondering if a ~tc78/75 or even an on3 78/75 would generate the same #'s as the s475. I really dont want to use a used turbo or a cheapy turbo as I dont want to have to redo pipes again...the downpipe is such I tight fit for how I lay it out. Really can only get a 3.5" DP in there as I like to run them into a dual exhaust over the rear axle and 4" just wont sneak through. If this was a fender exit this would all be a non-issue but this is primarily a street car that needs to be non-attention getting lol!!!

 

Plenty of ON3 78/75's out there pushing HP. VSRacings Billet 78/75 is a nice one Cheap too