jay_rich

iTrader: (8)

I was wondering, I have heard many different comments on this topic.

I am thinking of doing a twin MP T61 or maybe TC 62 (t3/t4) on a stock cube LS1 with a 6 speed for my 2000 FRC.

Now would the t3/t4 cause too much back pressure? Ive read some thread people saying the t3 turbine side causes too much back pressure and will choke out even a 5.3L.

Im hoping if I need to go T4 based I can fit a T4 up in my fenders.

The cam of choice will probably be a 224-228 durration with a 114-116lsa.

Thinking either a speedinc TU1 (225/225 113lsa) or the tsp224 (224/224 114lsa)

For now it would be on a stock motor (prob stay around 6200rpm), then down the road upping to a forged motor and rev a bit higher.

I would like to keep it capable to do 700whp down the road.

Thanks for any input

Jay

PRAY HRD

iTrader: (119)

A guy i used to know ran a cam just like that with twin 60-1 t4 turbos on a stock 346 and ported 243's if i recall and 8.?:1 cr and made 800+rwhp on pump gas in a chevelle. All home built too! User name was nitrorocket if you wanna look up his threads and see what you can find. GL

XtremeDime

iTrader: (16)

Should be fine with t3/t4, but I would get a t4 flange if possible.

jay_rich

iTrader: (8)

Also for the price would it be worth just moving up to twin MPT70s, I know they would be a bit overkill on a 347 but they are the same price as their T61.

Would be a T4 .68A/R

Jay

bad6as

iTrader: (17)

If you only want 700 just go with a single tc78

jay_rich

iTrader: (8)

No room in my vette for a single, unless i did a hinsen kit and I dont like the kit. My plan was a single 78mm rear mount but I cant do a single rear mount unless I cut the trunk out which im not doing.

So I am dead set on twins, bc I can fender mount them.

Same setup as a UPP kit pretty much

Jay

PRAY HRD

iTrader: (119)

Not sure how those would spool up on stock disp. I'm pretty sure he could have gotten close to 1000rwhp with the 60-1's. I'd say go no bigger than twin 62's but i'm no turbo expert by any means! Talk to Jose @ forced inductions on here. He will know what you can get away with if you wanna go bigger!

N2OBaby

I am no expert but why not twin GT-35Rs?

jay_rich

iTrader: (8)

I was kinda leaning toward MPs for the price. I also considered turbonetics t3/t4 62-1s since they are 721 a piece on treadstones site.


I would like to stay 700ish and under per turbo. im gonna be collecting all the parts over the next 8 months or so.

Jay

PRAY HRD

iTrader: (119)

Those 61's will meet your power goals now and later and you they will spool up quickly! Bang for the buck they're pretty good.

jay_rich

iTrader: (8)

thats something i wanted to hear. As long as the MP T61 t3/t4 will have potential to make 700-800rwhp efficiently im happy

Jay

71 chevy

iTrader: (18)

a 4.8 with a 230s cam(no low end cam) spooled two t70s at 3400rpms, hitting the wastegate 8.5psi at 4500 rpms(in third gear)

I think your 5.7 should spool those without ado

another thing that ive heard is the since the master power t4 turbos use the same basic hotside from t60 -t76, spool will be similar, but the t70 will give more headroom. the only thing to be worried about would be surge, and looking at the maps and plotting a 5.7 against it, I dont believe a 5.7 would go into surge with two t70s.

so im saying, the t60s would be AMAZING for your power goals, but the t70 would work equally as well, and shouldnt give up any noticeable spool since the hotside is the same

jay_rich

iTrader: (8)

After doing a lot of compressor maps on some 60mm,66mm and 70mm turbos for a stock 5.7L it looks like twin 66mm would be perfect, twin 70s seem to put it right in the sweet spot but once you start cranking the boost on them it seem to get close to the surge limit but the turbo speed seems decent.

Twin 60s look like they would be perfect from the 10-14psi after that your really turning some rpm on them. For my goals I think the MP T61s would be good but for future plans with them I feel they would hope me back a bit. I think some 66-67s (MP42) would be mint but seem to go for a bit more money then the MPT70s

So I think I will be keeping my eyes open for some T4 66-70mm turbos with under a .70 A/R

Hopefully I did my math right on the compressor maps, I based it all of a VE of around 95% and 7000rpm. So there are many variables that come into play that will change my plot numbers.

Thanks for all the help on the above posts!

Now to get some vendors to start a bidding war hahah

T61 and T70s seem to go for 599.99, now I shall price some MP42s and see!

Jay

IT_SS

iTrader: (5)

you may want to also consider the TC66, just a couple hundred bucks more

TurboS10

iTrader: (12)

J Ask Jose about some GT61's. They can do the exhaust however you want. He quoted me a killer price a few years back for 2. The 61mm Tnetics with the 62mm f wheel look to be damn close to ideal on a 347. The 6165 setup will do 900whp on a 355. Very close to a PT88 single but twins instead.

nitrorocket

iTrader: (12)

Look up old threads... PT61's with the GT35R wheels are great and spool pretty quick.

Ton of info on here... A few guys even built there own setups I've heard...