R5FORD

iTrader: (1)

Just a quick one for those who have a GT3071 or GT3076.. Do you find them laggy or are they a nice turbo to use on the road?

Im going down the GTX route but undecided on the 3071 or 3076.. I think the 3076 may be slightly laggy for the road?

NEIL A

iTrader: (6)

Im running a GT3071 with a 63 housing and it is alot less laggy than my old T34.63.
Boost comes im seeing 2psi by 1800RPM and 6psi by 2200 rpm then close to a bar by 3000rpm, and that is on a 7.2:1 engine.

R5FORD

iTrader: (1)

one of Harveys engines he's got 1.9bar / 28 psi at 3200RPM with a GT3076 so would probably start coming on boost at 2500ish rpm

what power you pushing out Neil?

NEIL A

iTrader: (6)

Not got a clue never had it on a dyno yet ,as the map is still being adjusted. Ive never actualy watched to see where it is making the peak boost of 32psi but it tails off to 27/28 at the top end.

ST Turbo

Im using a GTX3076 on mine, starts spooling at about 2000rpm and is about a bar at around 3krpm!

i wouldnt say they are a laggy turbo at all and i would defo recomemend them. The power delivery is amazing!

My comp ratio is around 8.5:1 and i have quite a heavily ported head aswell and it still isnt laggy!

fatmike

iTrader: (4)

I use a 3076 with a .82 ex on the road, 450 bhpish running 30 psi, and its certainly less laggy then my old t34.63. I use to run a .63 on the gt30 but I found a .82 going for cheap so I grabbed it. Go for one mate, you won't regret it.

R5FORD

iTrader: (1)

I'm definatly going for one just need to know if the 3076 is laggy s thats got the potential to get me the power I'm after and going by harveys dyno sheets it seems to come in strng at 3200rpm all the way to the limiter.

R5FORD

iTrader: (1)

what exhaust housing you got mate?

J1mbo

iTrader: (1)

Aaron, you want 530bhp don't you?

Use a 3076 if so, a 3071 won't see it.

The 3076 isn't too laggy, if I didn't want a t4 that's what I'd be putting on

R5FORD

iTrader: (1)

Yhep we said around 430rwhp.

I know i was thinking 3071 to keep the lag down and because the GTX has a larger compressor wheel it could push through more air thus getting the power of the GT3076.. but from the graphs your dad set me a normal Gt3076 hits 2 bar by 3200rpm which looks like it will make a extremely quick car plus the fact it should produce around 400lbs/ft at 3000rpm is even better

R5FORD

iTrader: (1)

judging by the GT3076 and T4 graphs I have the T4 dosent come in hard until 4000rpm where the GT3076 does at 3200rpm but then T4 has better top end power and torque.. but I'm assuming the GTX3076 will be just as good toped as the T4 but with an earlier spool up.

J1mbo

iTrader: (1)

Remember with dyno graphs, in the car they normal loose a little bit as they're not loaded up as much as on dyno, its not much mind.

I would go for a 3076, or see what the gtx3076 is like, either would make great engine I think!

R5FORD

iTrader: (1)

Its going to be a gtx jim

I think il go gtx3076 and see if we can break the 530 barrier.

J1mbo

iTrader: (1)

Should do it, are you changing engine spec to suit it?

R5FORD

iTrader: (1)

Scs plenum, wrc inlet, 2wd exhaust manifold and 8 injectors i think thats all were doing

J1mbo

iTrader: (1)

Be nice to change cams and get the most out of it! Should still see good power from it though

R5FORD

iTrader: (1)

Might do jim.. Il speak to Harvey and see what he reckons.. He didnt mention it tho

J1mbo

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Might be worth a ask

R5FORD

iTrader: (1)

Will do.. Il call tomorrow am as per usual

TimC

iTrader: (1)

Dont forget a GTX3071 will flow 56lb of air although at higher boost. That should easily see the 530bhp you want but with incredible spool.

R5FORD

iTrader: (1)

What does a gt3076 flow mate?

TimC

iTrader: (1)

On a previous thread somewhere, I seem to remember chip saying that a gtx3071 will make the same power as GT3076 but with the spool of a GT3071, The GTX3076 will make the same power as a GT35 but spool like a GT3076. Thats the way to view how the GTX series turbo works.

R5FORD

iTrader: (1)

Yhep i read that aswel mate but can the gtx range produce 60hp more on the smaller turbo just with an increase in the compressor wheel size

TimC

iTrader: (1)

About 55lb, a GTX3076 will flow around 65lb. A GT35 will flow about 66/67lb. A GTX35 is around 78lb.

R5FORD

iTrader: (1)

Hmmm wont the 3071 be at its limits at 530hp if it does actully make that power.

May be better to gofor the 3076 and have it having a easy time producing 530hp

TimC

iTrader: (1)

Its not down to the compressor size that makes the GTX range produce more air flow, its down to the billet wheel having the strength to allow an other bar or so of positive presure.

Staffi

iTrader: (1)

TT T38 AB07 Cam, apparently it's the nuts............

R5FORD

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the gospel

R5FORD

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O ok mate

TimC

iTrader: (1)

Thats upto you, but the GTX3071 will spool better and produce the power of the GT3076 but be around its limit yes, the GTX3076 should be under very little effort to make 530bhp but has the scope for more if you fancy it.

I personly would be going GTX3071 and having one hell of a driveable engine with a great spread of power although slightly less at its peak.

R5FORD

iTrader: (1)

I was thinking that aswel tbh mate.. Im sure the gtx3071 will push past the 500-510 mark and be extremly responsive and a hoot to drive

J1mbo

iTrader: (1)

Tim, your going off hearsay, not fact, they expect them to flow that much. The fact is though, the exhaust side is the issue, not the compressor, so by making the comp side bigger in Essenese your not gaining anything where you need it.

I'd be interested to see what oower they would make at a acceptable back pressure

R5FORD

iTrader: (1)

Jim what rpm would you expect a GTX3076 to start spooling up and producing good power/torque?

Rs1

iTrader: (1)

In terms of lag on the road its not even worth measuring the differance between a 71 and a 76(both on .8x) as it'll be minimal.
In terms of threshold.... or more important when does it get on full tilt imo realisticly you'll be looking toward 3.8-4k for the 71 and around 4-4.2k for the 76 but it will be dependant on spec/setup also(again both .8x)
Theres always the choice to come down to .6x but if you going to be holding in WOT for a decent length of time(vamx etc) or running toward the fun side of the rev range more often(track days) you'll not realy want the restriction of the smaller housing. This may also restrict.... ultimate performance of the comp. side. For a road car its well worth considering though.

qad

i have had a t4 on my 3dr love it my mate got a saff with gt30 we both didnt like it he swap it for a t4 and the car was better...i think the gt range turbo's sound good on a paper but dont think they work as well.. maybe try a T4??

R5FORD

iTrader: (1)

T4s to laggy mate. Iv just had a rs500 engine built and it has pretty much no power below 4000rpm and all the power up at the high revs

ajamesc

tell him to take it to someone who knows how to set up/build a car then lol mine dosent really have any lag with my m.a.d 500 conversion with a gt30

Rollinz

diferent car i know, but a mate has an astra GSI with a 3076 and he's doing 2.4 bar for 3500rpm

qad

My old 3dr comes in @ 2200 rpm with T4...driving along in 5fh gear @ 40mph and @ 2000rpm coming up to a round about i would not have to change down, it would pull like a train.. long time ago ronnie with the black 3dr had a gt30 change it for t34 and he love it.. my old 3dr is whitey car runs a t4 with no lag.. i can say this for sure big turbo's are not laggy, most of the times its down to the engine spec and mapping....same with the T34 its got to have the right housing and spec and mapping...
if anyone got a laggy turbo then take it to gsmotosport 07940 181847 for a set up if your not happy dont pay him!!!

R5FORD

iTrader: (1)

At 3200rpm the T4 has 14psi compared to the GT3076 which is running 32psi and has over 400lbs ft.. Yhe T4 is a laggy turbo but has alot of top end power