Iroc n roll

It's not for an F-body but all the same you guys know you're stuff. The motor is a caddy 4.9 PFI (from a 1992 deville). Completely stock. The turbo will be plumbed into the crossover pipe. The intercooler is a SAAB900 unit. A compressor bypass valve will also be used. I'm looking for low boost (around 7psi) and RPM operation will be from 2 or 3k to 5k (redline). Do you need anymore info? From what I remember the motor stock produces about 200/275 hp/tq stock, maybe a bit more. So what's a good turbo. Some people have recommended the T4, but there are quite a few variations of it. Which one is best?

83 Crossfire TA

iTrader: (2)

Those caddies are very mild, but decent engines. I really doubt that it will be happy revving to 5000, most of them really start falling off in the mid 4K range.

With 7psi boost on a 200hp engine you will at most have 300hp with a VERY GOOD intercooler. Based on that, depending on where you're planning on getting your turbo from it looks like any almost all of the T04's are reasonably happy in that range (except the S3) as well as the performance turbos in the T60-T62-1 range. With the T04's I'd probably look for an H3 or V1/V2, or one of the T60-T62-1 turbos, since they seem the best fit.

Iroc n roll

What A/R's shoud I look for in a T4? What should I look for in a T3/T4? Would I be able to find any of these in a junk yard? Yeah, the motor starts running out of revs more around 4800 or so rather than 5000

83 Crossfire TA

iTrader: (2)

Well, if you go T4 you should probably be looking for a .69A/R turbine or maybe one step down. With a hybrid you'll want bigger then the typical .63 turbine, there is a .82 that should be about in the right range but I've never seen a hybrid built with one. I think that there is also a 1.06, but I've never seen one.

Iroc n roll

What compessor should I use with the T4? Hybrids use the T3 turbine and T4 compressor right?...or are they just any combo of parts for both turbos? What are the specs on the grand national turbo...would that be big enough? BTW thatnks for all the info, this is some good stuff.

83 Crossfire TA

iTrader: (2)

T3/T4 hybrids use a T4 backing plate, compressor wheel and compressor housing bolted to a T3 back side.

The later GN turbos are basically .63A/R T3 turbines with proprietary GM compressors. The compressor wheel is about the size of an S3 T04, and a standard T3 60 compressor housing could be machined to fit it (as a matter of fact, things like the ford T3 60 inlet bell is interchangeable with the GN one, bolt pattern wise). Earlier GN/Type turbos can have all sorts of combinations, the most common being essentially a T3 60 compressor and .82 turbine. WRT to compressor sizing I’ve been giving you ‘best case’ suggestions, the GN turbo would be a little small, but it would work on your application. You’ll loose a little efficiency (run a little hotter), but it will work for what your talking about.

I’m not sure about the compressor question. The trim or type describes the compressor size (60 trim T3 or a V1 T04…), while turbines are usually referred to by their A/R.

Iroc n roll

http://cgi.ebay.com/ebaymotors/ws/eB...tem=1876698008

How about this T04? He doesn't give the trim but he gives the compressor A/R. The compressor seems a bit small. Is it too small or better than I think?...other than the fact that it's in dire need of a rebuild.

83 Crossfire TA

iTrader: (2)

honestly, I don't know what that is, but that compressor side appears smaller then any of the T04b's that I've seen a map for. It is within the range of the T04e's that I've seen, but that would make it way to small for your engine.

Either way, I don't know what his reserve is, but i wouldn't pay more then $25, maybe $50 if it was hard to find for what will end up being a core (I would trust anything advertized as should work but will need a rebuild)

Iroc n roll

I think I've found the ideal turbo. The guy says its new. I'm emailing him for pics. Here it is. Any thoughts?

http://cgi.ebay.com/ebaymotors/ws/eB...tem=2400889242

Iroc n roll

The turbine might be a bit big, but it looks pretty good, must be fresh from a rebuild. Compressor is .60 and turbine .84. Here's a pic.

Iroc n roll

And another pic. Yes it has the T3 flange (which will make it easier for me to hook up), but he says its a straight T04. Even if it is a hybrid, it'll be even better for me since that turbine might be abit big anyway.

Iroc n roll

This one doesn't look all that bad either, but it's a Holset turbo. Don't know too much about them. Any opinions?

http://cgi.ebay.com/ebaymotors/ws/eB...tem=2401166512

Iroc n roll

This one doesn't look all that bad either, but it's a Holset turbo. Don't know too much about them. Any opinions?

http://cgi.ebay.com/ebaymotors/ws/eB...tem=2401166512

Iroc n roll

Ok foget about the garrett....it sold . But the Holset looks pretty good. Looks like it uses a standard T3 flange and if its anything like a t3/t4 hybrid with a 1.00 turbine it should work great. Right?

83 Crossfire TA

iTrader: (2)

Some of the Holset's could be OK, they range in size just like garrets, but they are easier to find in larger sizes then garrets. That guy selling it sounds somewhat full of it, talking about 'stage 4' and 1.0 AR (Holset rates their exhaust housings in straight area in cm^2). Hard to identify what it really is, especially since the ID tag has been painted over, but looks like an H2_, I guess it doesn't make a difference since the sale is over anyway.

What are you looking to get out of this thing again?

In a lot of ways I like the holsets better then comprable garrets, if you have to room to package them (they're big honking turbos, mostly designed for trucks and heavy equimpent).

Based on your original description, you might even get away with something as small as an HX35 (the one used on the cummings dodge trucks). It will pump enough air for over 450hp at a pressure ratio of 2 and well over 550 hp at a pressure ratio of 3. The exhaust turbine will probably be a bit on the small side (will spool early), but if you end up with boost control issues you could always run a large external wastegate.

I've got the sick idea stuck in my head of trying a BIG holset on a 350 or larger engine

Iroc n roll

I'm really only looking for mild boost and power maybe 5-7psi to bring me a just over 300hp. Would a Holset H2 be a good fit? It seems like it would based on this guys description. If it's just a bit bigger than the stock sy/ty turbo on the 4.3 then it should be great for my mild 4.9, right? Is my logic sound? I don't want to go too big since the motor only revs to like 4,800.

It sounds like this guy is trying to explain the turbo in "garrett terms" which might account for his coming across slightly shady.

83 Crossfire TA

iTrader: (2)

OK, if the engine originally made 200hp then 7-8psig with a GOOD intercooler will put you around 300.

What you need to remember is that most of the turbos we’re looking at get more efficient as you build more boost (within reason, most do best in the 2.5-3 or more pressure ratio range, roughly 20-30psi), as you try to get it to work at lower boost levels it gets less efficient and you end up needing a bigger turbo then if you were running more boost.

WRT to the H2 turbos, I’m not sure. I’ve only seen a compressor map for an H2E, and I’m not sure what the letters at the end mean (this is the older Holset naming scheme which I don’t know and haven’t been able to find much about, and not for a lack of trying, in the 90’s they went to the HX___ naming scheme). I know that there are H1C’s and D’s and I believe that I’ve seen H2 C’s, D’s and E’s. Externally they all appear roughly the same size, but that doesn’t mean that they pump the same amount of air. Going off the H2E map that I’ve seen I’d say that that one is to big for your caddie, even with the most optimized setup you’ll be right on the surge line at your HP peak so I suspect that you’ll be below it at other points plus that it would not spool well.

WRT to the SyTy turbo, I’d say that that would be a bit on the small side for your setup. SyTy’s top out at about 4500 rpm (redline is at 4600 or 4700rpm) and this is pretty much from lack of breathing on the turbo’s part. They are pretty much topped out at their 280hp, and from seeing boost gauges installed on some of them that’s at about 18psi. Remember what I said about turbo efficiency? You won’t even be able to expect it to pump the same amount of air at 7psi, your not even close to being on the map at that point.

onebadwagon

i would check into a decent 60-1 with something like a p trim. that is a nice little turbo and should put you right in your useable range.
l

Iroc n roll

Do you know where I can get more info on Holset Turbos? I've been looking around for sites but can't see anything. I've been in contact with that seller with the H2 and this is what he gave me on the turbo

"It is a Holset 50mm T04E type compressor with a stage 4 turbine wheel and 1.0 A/R turbine equivalent"

He said it was bigger than a Sy/Ty turbo (which is bigger than a GN turbo correct? even the earlier ones?) so it should be a bit better of a fit. How would the 50mm compressor fit the setup?

83 Crossfire TA

iTrader: (2)

Like I've already said, "It is a Holset 50mm T04E type compressor with a stage 4 turbine wheel" means NOTHING WRT holset turbos...

If he's implying it's similarly sized to a 50 trim T04e... well that won't get your 300 hp at 5-7psi...

To answer your other questions, yea, the sy/ty turbo is slightly bigger then the GN turbo, but for that matter, the sy/ty turbo is more efficient (larger) below a pressure ratio of about 2 (14.7psi) then the T04e 50 trim (at over a 2 pressure ratio the T04 is 'larger', the compressor maps are completely different shapes)...