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Current thinking on turbo selection

foggyjames

foggyjames

Procrastinating since 2001!
Joined
Jan 22, 2004
Location
Nottingham, UK
Hi all,

Long time, no see! I'm vaguely making plans to resurrect Ryan's 700R (for the uninitiated: http://forums.turbobricks.com/showthread.php?t=60342), which I bought a couple of years ago. It currently sits without an engine, but is otherwise not far off being good to go. Sadly, I'm pretty out of touch with the current thinking on a couple of points.

Previous setup (prior to two aborted schemes, the first involving a B230 with big-valve 531 and a Holset bolted to a 90+, the second a SPM-equipped AQ171, header and Holset) was a stock FK, K cam, T3/T4 hybrid on a 90+, plus all the supporting stuff (IC, 3" turbo-back, MSnS-E, etc), which made 300/300 (crank) at 20psi.

I was impressed by the numbers RvolvoR made on his 242 (IIRC standard long engine plus cam, tubular manifold and Holset HE351 - circa 340 wheel at 17psi on E85), and decided this looked like a sensible formula. With a little less timing (on pump fuel) and a bit more boost, I reckon I should still be close to 400 crank.

Two questions:

1) What's the current thinking on turbo choice? If I had plenty of money to spare, and wanted to go a little smaller to aid spooling, I'd be thinking GT30-family. Or, on a budget, a Holset. Finally, it turns on that some of the BW turbos (S252, specifically) aren't silly money at all here. Where do they fit into this equation? I'm very out of touch with their sizing.

2) Tubular manifold...what's the latest on that? There were a couple of group buys running a couple of years ago. I do have a bag full of mild steel elbows which I'd be tempted to try MIGing up, especially given that a LHD manifold is in no way guaranteed to fit a RHD car.

Let me know what I've been missing for the past few years!

cheers

James
 
I'll admit I've more or less ignored E85, as it's not at all common here. How much extra timing can you typically run?

To be fair, my plan is to run circa 20psi with a "medium-large" turbo, and I get what I get. Anything north of 350 would be a result, as far as I'm concerned. It made 300 crank with a 90+ and a T3 hotside, so I would expect another 50+ with a tubular manifold and a larger turbine.

In other words, with a target spool point around 3k (a little higher is no biggie - spool promoting efforts include steps to reduce backpresure ratio (manifold and large-ish turbine) and an NA-ish cam) and shooting for somewhere in the 350-400 range, would you choose a GT30, a HX/HY35/HE351, or a S252.

cheers

James
 
My friend with a Dodge Caravan minivan, with a 2.4L 16 valves gain 1 second from 14.6sec to 13.6sec in 1/4 mile, with E85 and a tune with more fuel to get the proper a/f ratio and added more timing, but at the same boost level. 1/4 miles calculators says that's about 100hp.
 
Depends on how short he was of fuel before. My NA B200 jumped from a peak reading of circa 110bhp to 140bhp once the fuelling was adjusted to 12:1. I don't doubt there's an effect from the E85, but I'd be surprised if it accounts for more than 50bhp in RvolvoR's application.

Anyone got any input on the turbo sizing?

cheers

James
 
If you can swing it, the new GTX series Garrett's are damn nice. Think that's the route Doug's going for his next whiteblock.

I ran one of the HE351's and it was indeed fun when it woke up, but on LH, even with E85, it was a bit annoying down low, didn't really wake til around 3k, fill tilt by 3500. I swapped to a GT2871R and love it, way more down low, off-boost is happier, spool is like a 15g and the punch is about 3/4 of the HE351. One of the GTX3067's should be a nice setup.
 
gsellstr said:
If you can swing it, the new GTX series Garrett's are damn nice. Think that's the route Doug's going for his next whiteblock.

I ran one of the HE351's and it was indeed fun when it woke up, but on LH, even with E85, it was a bit annoying down low, didn't really wake til around 3k, fill tilt by 3500. I swapped to a GT2871R and love it, way more down low, off-boost is happier, spool is like a 15g and the punch is about 3/4 of the HE351. One of the GTX3067's should be a nice setup.
Click to expand...

Agreed
 
In that case, just put a holset on it then. Say an hx30 or hx35. Positive boost by 2800 rpm and full boost by 35-3800rpm.
 
Gt3071r. I use a gt2871r an like mentioned above it spoils like a 15g but packs a larger punch an is good to 400whp or more. If I wasnt using the car for drift I would get a 86ar turbine housing or go with a gt3071r or if money isn't an option GTX SERIES is pure awesome
 
Thanks for your thoughts, folks, and apologies for getting back to you. Some interesting options there. The GT/GTX series are certainly very interesting, but are likely to cost more than I have to spend at present.

What do people think about the s252...for example spool point, and "haul ass" factor relative to a Holset? I feel like I've seen a few people running them (or possibly their siblings?) around here.

cheers

James
 
There really is a practical boost and hp limit with pump gas. E85 is over 100 octane rating, so you get away with more boost or more timing that you just can't do on a turbo 8v motor and pump gas. I have tuned a bunch of 8v turbo Volvos on megasquirt, and you start walking a tight rope with detonation vs timing and boost around 18-20psi. You start needing race gas or something to raise the octane rating at that point.
 
The car has run at 27-28psi before, and I can entirely relate to what you're saying, so my plan is to keep it to 20 or so, for exactly the reasons you mention. The plan, in a nutshell, is to get it flowing better in the top half of the RPM scale with minimal investment, hence the interest in a manifold and rather oversized turbo.

cheers

James
 
qwkswede said:
There really is a practical boost and hp limit with pump gas. E85 is over 100 octane rating, so you get away with more boost or more timing that you just can't do on a turbo 8v motor and pump gas. I have tuned a bunch of 8v turbo Volvos on megasquirt, and you start walking a tight rope with detonation vs timing and boost around 18-20psi. You start needing race gas or something to raise the octane rating at that point.
Click to expand...


He's in Pommieland, he can get RON98 all day long... A popular large bore turbo Ford model over there runs 30 PSI on 98RON no problem..

My opinion is he should look into a turbo off of any of the 4x4 versions of that certain popular Ford Those things were good for right about 315-320 hp with a .48 a/r exhuast housing and just aout 390-400 with the "large turbo" 1993 version which came with a .63 a/r turbine housing and a slightly larger compressor wheel....

Ordinary 4x4 TB0384 http://www.turbomaster.info/eng/garrett_parts_list/465189-0003.php
Big turbo 1993, TB3403
http://www.turbomaster.info/eng/garrett_parts_list/452059-0001.php

Early hard spool, revs past 7500. Safe shaft speed.
 
Interesting thought, John. The car was previously running a more-or-less RS500-spec T3/T4 hybrid with the larger turbine housing, and that got us to 300 brake at 20psi (on 95 octane). The car felt good, and I'm tempted to stick with the devil I know. I know the manifold will help, but I'm inclined to go a bit larger with the turbo, too. Undecided!

cheers

James
 
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