VNT vs T28

[bigdur]

Next spring I'll be looking at track days for my 5 once I've finished all the niggly jobs and sorted a trailer, question is should I change my T28 for a VNT? Engine has a 285 cam. Appreciate any info you lot can spare on the subject regarding pros and cons.

[Eugein Offord]

T2?

[Markey Mark (BD)]

For me i wouldn't go any bigger then T25 for track maybe even T2/T25. As Eugien says the T2 is a good turbo for track too but its not going to work well with the 285 cam, your best bet is T25 unless you want to swap cams ;)

[BluntyR5GTT]

i think t25/t2 with 47 rear would be a great turbo for track

[bigdur]

What sort of boost can you run with t25/t2 and power outputs? I'll be doing it with a mate in a Mk2 golf Vr6 and don't want to be left behind!
Will that turbo work with my cam?

[tubbyG]

I run a t25/2 with a .47 rear with 285 cam. its a great turbo. Spools up reasonably quick, I rarely rev all the way to 7k but it pulls well all the way tho.

I run 20 psi (dont know how long it will last at this pressure) and its great fun and will give others a shock - as mr vxr found out last night;)

[Alex]

I use a T2/T25 on track with a 285 cam and it works really well. I only run 11 psi but will be upping it a bit more soon. I think if I was ever to change the turbo I'd go for a full T25 with having the cam though..... :)

[Eugein Offord]

ive always found with a std rad that every increase in turbo and boost gives less time on the circuit before the cars brakes and engine temps rise too high and the car needs to slow right down for some cooling laps....Plus the faster the car the harder:burnrubber::burnrubber: the crash>>>>>>>>>t2/25 at a bar or18 psi is quick...............:)

[Eugein Offord]

the best money ive ever spent for a track car is Brand new slicks ........... unbelievable grip............

[markey b]

VNT! at a bar of boost my car would leave caterhams for dead down snetterton straights

pro's = big turbo with hardly and lag, the 'pop' out the exhaust when the vanes change

cons = cost and getting it set up properly, boost spike

[raj]

cons = cost and getting it set up properly, boost spike

this is what swayed me away from a vnt set up on my old r5. too much faffing about..but then i have no patients:rolleyes:

[jesus in the seat of a 5]

ive always found with a std rad that every increase in turbo and boost gives less time on the circuit before the cars brakes and engine temps rise too high and the car needs to slow right down for some cooling laps....Plus the faster the car the harder:burnrubber::burnrubber: the crash>>>>>>>>>t2/25 at a bar or18 psi is quick...............:)

:agree:..indeed, i run a t2 on the rowan coupe at a bar of boostings...tis plenty as hugh jeans has said..., it will rev to 7k neigh worries and peddles nicely all day out on track, i did plan on changing it but it gives me enough fun and the car behaves s well ..which counts for a lot!!!, i plan to run a t25 or vnt on the hillclimb car...which ever i depend on putting on etc..may try both like...:), that depends on friends...hint , hint alister/andrew cooke...:wasntme:;)

[Logg]

I'd agree with Huge Jeans and the blessed Jesus a turbo as close to stock is great for track action. Very little to no lag and not enough power to get you into to much trouble with heat transfer and speed.

The real question is how much power do you want. Then pick the smallest turbo that can provide that power efficiently.

[bigdur]

Thanks guys, looking for enough power to keep with a VR6 mk2 golf, now I've the cost of another turbo to think about, tempted to get another carb to match and keep my T28 and carb as is for the pod.

[BluntyR5GTT]

Thanks guys, looking for enough power to keep with a VR6 mk2 golf, now I've the cost of another turbo to think about, tempted to get another carb to match and keep my T28 and carb as is for the pod.

t25/t2 18psi and 285 cam should easily be able sort that golf out :agree:

we can do a t25/t2.35 for around £375 all in

[bigdur]

t25/t2 18psi and 285 cam should easily be able sort that golf out :agree:

we can do a t25/t2.35 for around £375 all in

Sounds very interesting, when would I see it boosting?
Carb is currently set for 20psi on the T28, would that be over the top for this turbo arrangement? I'm not looking to get mega miles from it as it's an occasional weekend blast/track car.

[BluntyR5GTT]

well this would have 360 bearing so could run 20psi if you wanted to but its always best build another carb up as the airflow will be diff.

it shouldnt be too far from a t2 tbh i know the ones with .47 rear see full boost around 3.5k so id imagine a tad before that.

we could even look at machining a t25 shaft/turbine into the .35 housing

[bigdur]

Little lag and big power is what I'm after, happy to investigate options, has that been done before?

[BluntyR5GTT]

not sure if its been done before or not? but i know we have just machined a t28 shaft/turbine into my t2.63 housing

the turbo i mention would be perfect with a 285 cam :)

[Logg]

Well what do you class as big power remembering that anything over 220ish bhp will become an issue to fuel with the carb still in place. look at garretts website they have quite a few small turbos with 200hp ratings.

http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/turbo_comparison_sheet.htm

[bigdur]

Sorry, should of specified, 200-220 would be ideal IMO.

[BluntyR5GTT]

you wont see them power levels on a t25/t2 mate

[Eugein Offord]

you wont see them power levels on a t25/t2 mate

not unless you go for 2bar..............:)

If it was me i'd let the golf past on the straights they a'int so quick..and have it in the braking zone and corner exit speed....... i feel that as little as 35% of time on a lap at some tracks, I uses full throttle the rest is trying to slow or turn...........


i had a polite talk to an official at mallory years ago who said "You cant overtake in the braking zone".. i told him "I wasnt in my braking zone"........i cant recommed the ferodo ds2500 enough.........they will cut the stopping distance in half.....on std set up.. also good tyres..... your mate will think hes got a quick car but slower round a track than a GTT....:)

[rs250nut]

not sure if its been done before or not? but i know we have just machined a t28 shaft/turbine into my t2.63 housing

the turbo i mention would be perfect with a 285 cam :)

Yes but will it be though? Not trying to be a knob or anything but the whole idea behind fitting a t28 with a big cam is to get it to breath better up top not to stifle it with a tiny exhaust housing. Dont get me wrong hybrid turbos can be good.

In a perfect world there would be no lag and we could all make a 1000hp but sadly things are not that simple, you have to ask yourself whats more important and what do you want to use the car for?

[Slim]

Im running that now... and it doesnt help lag too much to be honest.. but i feel it is restricting power tho.. gna put back my .49 back on..

[bigdur]

you wont see them power levels on a t25/t2 mate

Well possibly not but heres dreaming lol

[Scoff]

I think if I was building an all-round track GTT I'd want high compression, a BP270 and a real T25 at 1 bar. :)

[Woznaldo]

When you say high comp, what figures are we talking? 9.0:1? I think that's where I'd go but on a Twin Scroll and maybe give a Cat Cams 327 a whirl?

[bigdur]

It would be very handy to have a list of all the turbo types inc hybrids, where they start to boost, what the maximum safe boost levels are and approximate hp levels. :D