Not only the rpm vs. boost concerns, but then you have to factor in the shifts in compressor maps, i.e. the 76 might make super high peak numbers on one displacement, but choke off quickly on another and not make as much power with a shitty curve...

That's why I wonder what the TOTAL characteristics would be like for a 346/347 T-70 combo... Because if it would peak well up to the point of running race gas safely = good idea. If it might squeeze the numbers or fall a little bit short, dropping off at the end of the powerband badly due to a choking turbo = bad idea.

Lotsa good ??? here.

 

Man, deciding on a set-up is the biggest dilemma for me.

The second I do, the fun begins.

 

I thought you already had a PTK w/ 70 kit?

 

I do... but when I go forged and up the boost, therein lies the dilemma to which all these questions relate.

 

what kind of heads and cam are you running? It would be cheaper to get a bigger intercooler than a turbo.

 

Stock heads/cam for now, but I was thinking about a Z06 cam and 6.0 heads... 8.5 CR with 346/347 forged pistons/rods... I wonder how the T-70 would handle all of this?

 

I am doing pretty much the same thing with my build. Forged 8.5:1 346, Dart 225 Heads, LS6 intake, Cam???, and a 6.0L manifold based T70 hybrid 66mm turbo kit. I figure the turbo will be suitable for my goal. Good spool time, capable of producing the HP goals I have set, and it wasn't $1300. I will probably pick up a T76 to add later on. I am planning on DFI Gen 7 or BS3 to tune with. Both wired piggyback to the stock PCM. I set my Hp goal at 550rwhp, But I am gonna see what I can get out of this 346.

 

You will need to 6.0 heads for sure I would try and get some ported heads if you can such as the 6.0 cnc'd heads from TSP for only 880 dollars and get a custom ground turbo cam something a little better than the z06 cam although that cam works really well with a turbo. Even if you don't want to spend the money on the heads the 6.0 heads will work better than your stock ones. Good luck and I would not buy the 76 turbo until you use what you got first since you already got it.

 

You guys are telling me what I want to hear. Thanks.

**** it. For now, I'll start getting prices for the engine build and install/tune for max 346 cid pump gas power. If it's 650, then it's 650. If it's 600, then it's 600. If it's 700... etc. I just hope whatever limit I reach on the stock computer for pump gas, I don't reach because the T-70 is too small.

 

If you don't mind sharing, are you building up your block or buying a new block from a sonsor/non-sponsor?

 

I am using the block out of my 98 Z28. No need for a new one. I am going to use Mahle factory bore -16cc dished pistons and some H beam 6.125 rods. I was going to have the factory block honed out for some 3.905 pistons but didnt see the need. This 346 is only going to be in the car for as long as it holds together. When I get the car up and running I am gonna do a 370 or 408 iron motor built for a large amount of boost.

 

I'd go with meth to be safe and make more power, though I'm pretty sure you could run 700 on pump only.

 

I'm TTT'ing my own thread here because I wanted to ask a question...

Can I reach the 8.5 CR with just buying the pistons, the conrods, and 6.0 heads on my stock block with the stock crankshaft? I am about to start buying parts... Better spend the money sooner and make it disappear before my wife notices it.

I'm just gonna have a custom cam made because turbo cams, well, there's just too much debate over their approach and I'd rather have my installer grind one.

Any help will be appreciated... And, yeah, I'm sticking with the MPT-70 and seeing what this sucker can do... Soooo TTT.

Thanks.

 

Anybody done up a 346 that can help me with this question?

Thanks.

 

I'd like to know as well. I found a MP T70 with a .96 a/r for a damn good price here locally.

I'd really like to know how fun this turbo would be for a street turbo. Spooling characteristics(sp?) on low comp LS1 and HP/TQ potential as well.

My GT42 spools a lil slow but should be a nice strip turbo once I get things all working together...tune/tranny/driver

So any turbo guys like Jose/NOSjohn etc etc...have any input on how a MP T70 would fair powerwise on a low comp LS1?

Thanks,
J

 

frcefed98:
I am by far no expert on turbos, but I think on a low compression 346 combo like we are using the T70 is better suited as far as spool time, and should be more than capable of producing 550+ at the wheels. I will probably go to a T76 later on, but I plan to see just how far I can push my 346 T70 combo first. I mean hell, if all I can get out of it is 450 at the wheels than thats all it will get. Then I will go bigger in search of more power. I think I will meat my 550hp goal with the T70.

 

Well, I will be certainly finding out soon, i.e. How far the T-70 will go on street/pump 346... The spool right now is great, even in spite of my 3.73's. In this thread, there seem to be a couple of people that feel the T-70 can go over 650 rwhp.

Anyhow, any input on the motor? I know many stroker set-ups have super low CR's. With the stock crank, can 8.5 or lower be achieved with the right sized pistons/rods and 6.0 heads?

In all seriousness, (Mods) do I make a thread instead in the Internals section? I can see that my question has turned into less about FI.

I've seen few set-ups here with strengthened insternals on the stock block. But I haven't seen one with 8.5 CR yet. I wondered if it just wasn't possible or just not usually done.

 

Wickedred, GET IT RUNNING ALREADY I NEED SOME INFO!!!! I've read where the T70 is good till ~850 so about 600-650rwhp maybe??? I just want a fun turbo on the street, a quick spooler that'll produce a lot of power early in the powerband. Making another DP is cake so I could just swap between the GT42 and the T70 when I need too. My understanding of turbos is still pretty lame, but I'll keep reading up to see if I can find some more info. I def don't want to pass this deal up.

I'd like a really quick spooling turbo for the street, unlike my GT42 where it takes it awhile for it to come alive.
I was watching a video of a GTO with a T70 out on the street and man that thing spooled fast and the tires lit up real easy....

What we need is a sticky up top with a Turbo selection guide for 346's, 370's,383's 408's on up LSX builds so people can reference it when they need to choose a turbo for their LSX based vehicle.

BB, I'd pm a sponsor like W2W, TSP, LME, TR to see if they can help you put a package together. Just let em where you compression needs to be and see what they come up with. I don't think 8.5 would be out of the question with a set of 6.0's ported and polished, a good FI specific piston and the stock crank.

J

 

Oh I will... I was just wondering if anyone had done something like this with the stock 346 crank.

Camming and with meth, I hope my T-70 can put out ~650-700 rwhp. That would certainly be nice, indeed.

Thanks.

 

Is your question whether you can make a low compression 346ci?

Mine is 348ci, and 8.2:1 or around there. Custom pistons. Stock crank.