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stevieturbo

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18th Nov, 2006 at 01:03:28am

I read a few posts with people being concerned about big blowers being laggy.

What are the biggest ones people have used though ??

Anyone tried the likes of a GT28 ??

I ask, because my own T3 based turbo would seem fairly large ( and very old ) and whilst it was laggy, it wasnt so much it bothered me.

Ive fitted T63 and T70 units to modified Subarus, and despite them being huge, they really werent laggy at all, all things considered.
Even the T70, which is pretty f**king massive would make over 2bar around 4000rpm.
That may sound laggy, but it really isnt !! It is making good useable boost from 3000rpm, which isnt much worse than an early WRX, except its making a lot more power at that time.

Bigger turbos are slower to spool, but big compressors also shift a lot more air at those speeds. So whilst you should lose....you gain it back again.

Just curious to see what people have actually tried. As although small turbos do work, having used a lot of biggish turbos...they can also work very well, when ya just think they shouldnt.

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turbodave16v
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18th Nov, 2006 at 01:17:01am

Pretty sure someone used the unit off a 2wd cosworth, and it would barely spool up? Don't remember who it was though - there are pics of it sat in the engine bay of a red clubby estate.

I guess you could find a turbine flow for one of those, and knowing that that is too high, work backwards from there as an upper limit?

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18th Nov, 2006 at 01:21:48am

Didn't TurboPhils mate Mike try a T4 for a few hours???


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18th Nov, 2006 at 08:49:33am

On 18th of Nov, 2006 at 01:21am Tom Fenton said:
Didn't TurboPhils mate Mike try a T4 for a few hours???


LOl, yeah. Saw this thread and instantly thought of Mike. I'll point him in this direction. Hope fully he'll even put some pics up of some "serious" blowers on the "A". LOL. *smiley*

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robert

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uranus

18th Nov, 2006 at 10:01:02am

i immediately thuoght of mike too phil lol

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stevieturbo

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18th Nov, 2006 at 07:21:57pm



On 18th of Nov, 2006 at 01:17am TurboDave said:
Pretty sure someone used the unit off a 2wd cosworth, and it would barely spool up? Don't remember who it was though - there are pics of it sat in the engine bay of a red clubby estate.

I guess you could find a turbine flow for one of those, and knowing that that is too high, work backwards from there as an upper limit?



Dave.

My compressor is off a 4x4 Cossie. The Metro cover was machined to accept it. ( dont know what the actual trim etc is, for a comp map. I only know its the same....as one time my turbo blew up, I stole the mates Cossie turbo to get parts to fix it lol

When I eventually take the car apart, I will measure.

This was mated to a T3 0.36 AR turbine housing.

Yes, it was laggy, but this would defo improve with modern boost control, and mapped ignition and better fuel control, and of course higher compression

Even off boost, the engine was very torquey, so it wasnt a bother to me. You could get caught in the wrong gear though.

But full boost ( circa 20psi ) was achieved around 4000rpm and it pulled hard to over 7000rpm. So whilst laggy, it still had a very useable power band, and would still pull WOT in 4th from around 1000rpm

Now I dont know how a GT28 compares to my T3, but I would suspect it probably flows more air, and spools faster.
best of all, Ive seen a few on ebay at sensible money.

I enquired about how the GT42 units perform on Evo's Ive seen fitted with them. Obviously they make silly amounts of power. But have you seen the size of them ???? One guy told me, that with well sorted cam specs and timing, they can make full boost around 4500rpm, although I think under 5000 would be more accurate.

Point is....big turbos arent always the lag monsters people think they are. The GT42 scenario is extreme.
A friends T61 ( might be a 63...cant rem ) powered 2.3l Subaru, spools faster than another friends T34 equipped Cossie.
When we upgraded another Subaru from a T61, to the T70, there reall was little change in spool. And first time out, at only 1.2 bar or so, the power difference was staggering !


Edited by stevieturbo on 18th Nov, 2006.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will


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stowmaket suffolk

19th Nov, 2006 at 09:18:02am

i think ceramic bearings will be a big help to if you can afford them

always looking for them bigger bunches of bannanas

fab

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19th Nov, 2006 at 10:41:50am

agree with you te's are reall monsters, I made a run in an audi sorting 575 bhp with a te71 at 2.5 boost at jp beltoise track, full boost was at 3.500 rpm feeling difference is awesome, but there is nothing comparable for a small 1300, I think that the big difference is the small a/r used on these truck turbo, with divorced high flow waste gate.

which gt28 are you chasing? t25/28 from fiats/c20 or real gt28.


stevieturbo

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19th Nov, 2006 at 11:57:03am

Ive seen a few Rover based GT28's, from some petrol turbo car they do ??
Not chasing as such, still thinking out loud.

It was a few weeks ago I seen a couple for sale on ebay.

Or a Nissan 200sx uses a GT28, as I recently had one off a friends car to fix the oil feed. I should have measured the damn thing while it was apart though :S
Its virtuall lag free, although its on a 2.0 of course.

The Rover one listed was a GT28RS from what the parts listing said. Think it was a GT2856

Id have thought the exhaust side would be small enough to spool up a fairly large compressor, which should be a good thing all round.

There is one listed now on ebay, off a Nissan the guy claims.
Even more interesting, is the fact the compressor cover looks similar in style to a Mini turbo.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will


fab

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19th Nov, 2006 at 03:58:17pm

I've found a t28 map (t25/28) some times ago,will post if wanted but really too large, about 350 flow......
about gt28, their' is a lot of china's made, you can see it as they don't have the air research scribed in the compressor hsg, carefull.
the garrett's gT28rs have their map largely available, again mini haven't enough flow for it
I know little about t28 used on fiats coupe and Nissans,will make some work on this.
I know some that have machinde t25 hsg to take t3 comp wheell, making a great efficient turbo, but this need professionals machining , balancing etc not really sheap!
what I know is a good t25 (55comp trim and 0.49 exhaust) or t3 45trim 0.36exhaust will make what you need in term of revs peps and efficiency


modifiedminis

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Fixing my car....

7th Dec, 2006 at 08:15:58pm

I am running Coosy 4x4 compressor wheel and housing on mine.... the exhaust housing is still .25 A/R the compressor housing is .42 A/R.. it takes a slight bit longer on the initial spool up but when it does boost it comes in hard and fast...

Here is a comparrison...



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