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Effect Of Smaller Comp Housing.

Daboss

By Daboss,
in Engines & Forced Induction

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Daboss Experienced

Daboss

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Hey forum just a general knowledge question here. I used the search function, but found no topics on the subject. I just would like to know what effect what a machined 3076r comp housing have on a gt35r?

Faster spool, slower spool, same spool, less horsepower at same boost or same horsepower at same boost?

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VB- Veteran

VB-

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think i read a while ago from someone of the xr6t persuasian that swapping from .5 to .7 on a gt35 is worth 20 or 40 kw in the top end or someting, not a massive amount... i'd imagine spool would be effected relatively proportional to power

Daboss Experienced

Daboss

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think i read a while ago from someone of the xr6t persuasian that swapping from .5 to .7 on a gt35 is worth 20 or 40 kw in the top end or someting, not a massive amount... i'd imagine spool would be effected relatively proportional to power

Hmmm so where would the .6 get you? Would you still have the top end capability of a 35r with a somewhat quicker spool time? Or would the effect be negligible? Would it still make more power than a 3076r of the same specs?

StealthX Veteran

StealthX

Posted
Posted

That hybrid 35r would prob make better powar than a 3076r, purely because it's got the larger rear, and less exhaust restriction.

I'd say response would be the same, the comp. wheel's inertia is the same, and the hot side is unchanged.

However you'd probably make more/better power at lower boost levels, and I'd imagine less power at higher boost levels.

i.e. it would move the efficiency range of the turbo down a tad.

think of it like installing a smaller profile camshaft, just makes different power at different revs.

that's my $0.02...

discopotato03 Grand Master

discopotato03

Posted
Posted (edited)

It wouldn't work because the inducer diameter of the 82mm GT40 56T compressor wheel is larger than the 76.2mm GT37 56T wheel . From memory the GT40's inducer is ~ 61mm where the GT37's is ~ 57mm . The compressor housing on a real GT3076R is port shrouded and the radial surge slot is positioned to match the height of the GT37 wheels lower or splitter blades . It wouldn't be right for the GT40 wheel and I'm not sure if there is enough material in the inner shroud to take a GT40 compressor .

The early XR6 turbos used a 0.50 A/R plain snouted T04E compressor housing and I can't see why you couldn't fit the plain snouted 0.60 A/R version of that housing if it was profile machined to suit the compressor wheel .

To me it sounded like Ford only wanted to run low boost on the early XR6's and having a GT3582R with the largest turbine housing and the small ratio T04E comp housing would have given them low hot side pressure and reasonable gas speed on the cold side with low boost pressure .

It really shouldn't be too hard to get good torque out of a twin cam 24v 4L turbo engine but as usual you can't choke it up on the hot side if you want a reasonable rev range - and reliability .

Personally I think a GT35 based turbo is a bit marginal on a four litre engine and a T04Z or GT4088R would have been better , trouble is they don't have a "T3" mounting flange or an integral waste gate .

Garrett do make a port shrouded version of the 0.70 A/R T04S compressor housing , the generic GT3582R usually gets the plain snouted bell mouthed version of it .

http://www.turbobygarrett.com/turbobygarre...R_714568_10.htm

A .

Edited by discopotato03

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