R33 210rwkw Major Boost Drop, No Top End?

[GTshortie]

Hey guys i've got a R33 gts25t series 2 with the following setup:

Trust FMIC, Garret T3/t4(rated@350hp i think) t3 flange std mounting position, Trust Pod Filter, Custom Stainless steel Turbo dump/front pipe(liverpool exhaust), Catco Hiflow cat, Fujitsubo Super Legalis R catback. Apexi Powerfc, Apexi Avc-r set at @1.3bar(18.85pounds). Also Tomei Metal Headgasket so lower compression, Cp Forged Pistons Shot-peen rods, Sard 550cc injectors, Nismo Fuel Pump. engine rebuilt 12000kms ago.

Now i've got all the details out of the way this is the problem.

got it dyno tuned with Hitman a while back i'm VERY happy with his service and the tune TOP BLOKE, HONEST just like how others has described his skills and expertise and the results are;

[email protected] or 18.85pounds@ around 5000rpm (REDLINE on graph) AND

[email protected] or 14.5pounds. (BLUE line on graph)

i hit full boost nice and early around 2800-2900rpm on 1.3bar BUT the boost doesn't hold and by the time it approaches redline or even at 5800rpm boost HAS DROP TO 12pounds from 19pounds. and POWER drops too from 5000rpm onwards NO TOP END.

We did Mutiple runs hitman spent a good 1 1/2 hours after the final tune trying to keep the boost up but nothing work, tested the cat and its not the cat set the boost controll or full 100% solonied duty no good also.

Knocking level on POWERFC less then 20 on the Handcontroller so its pretty good.

HOW COME BOOST DROPS SO MUCH??? WHY IS THERE NO TOP END??? Is it the TURBO or maybe something else? any opinions??...

[raz0r$harP.UK]

Turbo too small..running out of puff

[paulr33]

what size exhaust? do you know what size a/r the turbo is ?

[paulr33]

try a dyno run with the dump pipe disconnected and see if get the power back and boost doesnt drop off. may indiciate restrictive exhaust

[Links]

Was about to say as paul said it could be due to a restrictive exhaust unable to flow enough..

[discopotato03]

T3/T4 hybrid turbos are a real snake pit . Their original aim was to have a light weight (when compared to T04) T3 based turbine and hang a SMALL trim usually T04E compressor and cover on the cold side .

Back yard spares and Turbonetics take a look at them and decide that large trim compressors look much tougher and flog them off to the uninformed . Trouble is the poor little T3 turbine is going purple in the chops because the large trim compressor is trying to move the extra mass of air it can bite into .

The other problem is Wallys back yard turbos insists on boring out T3 or Skyline turbine housings for bigger turbines - the nozzle inside the housing gets machined away which you can't see and generally lag and or surge is the result .

The best T3/04E hybrids not surprisingly come from Garrett but for the money and real estate they take up the GTBB's do a better job .

Cheers A .

[GTshortie]

Not sure exactly on a/r sizes of the turbo, is it usually stamped/printed on the turbo itself? can i usually see it if i don't remove the turbo itself?

Its an original garret item that i got brand new about 2 years, i might consider a dyno run without the dump pipe connect and see if i get different results.

its 3" turbo dump front pipe to the cat, then the fujuitsubo super legalias R cat back tailpipe is 117mm, main pipe is 70-89.1mm. similar size to my previous exhaust apexi N1.

[R31Nismoid]

HOW COME BOOST DROPS SO MUCH??? WHY IS THERE NO TOP END???

what are you talking about dude??? The top end if the better looking part of that graph, even if it isnt totally smooth

The boost dropping off is only due to your turbo which is my guess as disco has already stated... they are a very random thing at times.

I'd be more worried why there is a dip around the 96-120km/h which looks more like a typical stock ECU dip.

[GTshortie]

Thanks for the inputs guy, this is a graph during the early stages of tuning.

its not even redline(7000rpm) yet but look at the power drop at top end.

i'm pretty sure a r33 gts25t isn't meant to do that in power especially if running at 18.85pounds of boost.(1.3bar)

[R31Nismoid]

Again, its more than likely the turbo...

And its hardly dropping anything @ the top... a 10-15kw drop is nothing to be worried about with a tiny turbo.

Its expected

[GTshortie]

Isn't a T3/T4 like a garret version of the HKS 2530, or is it smaller?

[benl1981]

does that turbo bolt up to same dump pipe - just wondering if it is similar to a HKS2530 where you can use your old dump and manifold etc..

[Bass Junky]

Well, you are saying that the turbo is rated to 350 hp.

210 rwkw is about 270 at the fly, maybe 250.

270 rwkw is 360 hp

250 rwkw is 335 hp

Turbo running out of puff.

[R31Nismoid]

Isn't a T3/T4 like a garret version of the HKS 2530, or is it smaller?

Not really

Have you read what discopotato posted yet?

[GTshortie]

Turbo connects to the 3" dump/front pipe, can't use the standard dump pipe.

sorry guys i have read what discopotato posted but i don't really understand it. ''wally's backyard turbo?'' its a genuine garret item tho.

(i was always under the impression that a HKS2530 would of been a similar size to a t3/t04, rated around 350hp, and then you get the HKS2540 which is similar size to a T04) hahaha sorry if i'm a bit stupid.

but i'm posting at work. i really appreciate all the feedback guys

So reckon a NICE big turbo 3037's, GT30 will give me power around 270rwkw?

[R31Nismoid]

sorry guys i have read what discopotato posted but i don't really understand it. ''wally's backyard turbo?'' its a genuine garret item tho.

he means something that someone has made with no reall technical mind or perspective.

Just put a front and a rear wheel on and hoped for the best, obviously it has not worked.

If you want more power, do a search, all been covered before

[bazr33]

well when ya have a look at it

ya have a worked engine, with a piss fart turbo hangin off the side

havin the turbo spoolin up and hitting full boost that early

looks to me the engine is goin way harder then what the turbo is producing. and cant keep up .

Your engine at the state you have it now, would be capable of makin 300rwkw ( from what i hear) and have a 350hp rated turbo on the side at 18psi.

Would you believe the exhaust would be so restrictive?

is it a stock exhaust ,

is it a 3 inch dump ?

do you have a different AFM?

let us know what the problem is, if i encounter it later on.

THanks

Barret

[GTshortie]

1. Not a stock exhaust (Fujitsubo Super Legalias R),

2. 3 inch Dump/front pipe right after the back of the turbo,

3. Standard R33 Gts25t AFM, (been told that there is no point of me changing it to a z32 since i only have 210rwkw) 225-230+ require Z32 correct me if i'm wrong.

FROM what others suggest its possible its just the turbos problem.

i've pin pointed it down to these possible causes

1. Turbo obviously too small

2. Dump/Front pipe (3" too big maybe, for this small turbo so it can't compress the air <same concept as having a 4" or 5" exhaust on a N/A lancer that would perform better with a 2 1/2">

3. AFM (i doubt it tho, at this power range 210rwkw i've been two by a few tuners that the std one should be able to handle it)

[bazr33]

it wouldnt think it would be the 3 inch dump

i have a split dump 3" with a stock turbo , on 10 psi doin 187rwkw

obviously your tuner, has tuned ya power fc to all your mods.

Have you done compression tests?

with the AFM your not really far off 225rwkw, and if your goin to get a bigger turbo, you will have to consider it .

Pretty much all i can see is you have all the supportin mods just need a bigger turbo

Would think something like a gt30, or something in the gt3* range

or even a gt2835r

Also another thing i would consider later on is cams, if you havent already done that. make it a bit more reliable and safe.

[paulr33]

drop the dump pipe off and let the turbo vent out and do a dyno run

see if you see the same problem. if so that rules out exhaust too small. if you make good power and the boost doesn't taper off then your exhaust system is too restrictive