Hi,

Does anyone know which of these two units will spool faster, given the same application, i.e. were the VF35 to be swapped out in my STI8 PPP for the MD321H (Assuming optimal remapping in each case)?

 

I swapped a MD321H in for my VF34 on a 2.5 and the spool was similar, prehaps couple hundred rpm in favour of VF34

 

ST420 another one to look at maybe if cost is a iessue

I made 412bhp on the 380 turbo they do with a little meth

 

I doubt you'll find a quicker spooling turbo than the VF35 (apart from the TD04 from the WRXs) but the VF35 is a 340bhp turbo and the MD321H is a 400bhp turbo so the latter will involve some compromise with spool. I do recall one graph on here where the MD was as good in terms spool characteristics as a VF28 (another low-mid 300s turbo), which is deeply impressive! Cracking turbo by all accounts.

 

Harvey has a new up-pipe for the MD321H which is supposed to help even more.... mine is a touch slow getting going, but then all hell breaks loose and it's 2 bar and beyond. (ecu limited to 1.65 bar & 392 bhp actually !)
I changed the whole exhaust system and de-catted too, so can't compare like with like, sorry.

dunx

 

That makes for interesting reading!

So basically I appear to be spoiled with my VF35. I'd like to have the car make 400bhp but still improve on the low end throttle response. I know 400hp is beyond the VF35 and my ideal would have been a 400bhp unit with faster spool characteristics than the VF35 but it sounds like this isn't going to be possible.

OK $64k question:

My car already has ported headers, modified induction and a slightly optimised PPP map. If I do the following would anyone hazard a guess as to whether a MD321H will be able to spool faster than my Stock STI PPP VF35 setup:

Lightened crank 'and other' pulley set from CDF Racing
Get the MD321H ported (if it isn't already)
Ultimate Racing low impedance 785cc injectors (with circuit for high imped. conversion)

If I can best the car's current spool-up and hit 400hp on pump fuel (without going so far as stroking) I'd be VERY happy. Do we think this is possible I am I just being

 

You can't expect a 20% bigger turbo to spool like the smaller one.

LOL, you need NO2....

dunx

 

Does indeed Dunx The up-pipe is not specific to the MD321H but is designed to work well with GT Spec headers (which many people with MD321Hs are already using).

I fitted this up-pipe last month and these are my thoughts as emailed to Harvey:

Spool - slightly better (earlier). On a sequence of uphill bends near home, I was able to accelerate out of some of them using one gear higher;

Throttle response - definitely better - much better!. Going through the gears, even less response time for car to 'go' after every gear change - virtually instantaneous in fact;

Torque - more mid range thump;

Top end power. Doesn't seem quite as eager but I think that's because of the rise in mid range torque making top end torque seem less; Paul at Zen agrees and the power graph verifies this.

Hope this helps

To the OP, an MD321H with Harvey's up-pipe on GT Spec headers spools pretty much as quick as a VF35 on standard headers and is a massive step up in performance

 

more like 380bhp with those upgrades. Put in a FMIC and fuel additives then you'd get closer to 400.
The MD will always spool slower, not quicker, whatever you do but the difference would be small

 

Buy a MD321T its the same price as the H. No problems with spool on a 2l and you will soar past 400 without the need to add more mods if you dont hit your target bhp.

 

Sorry was a bit slack, obviously.... it's a header related up-grade rather than a turbo specific part, "my bad"

So you rate it then

dunx

P.S. I wonder if he has one in stock....

 

Deffo rate it Dunx - get one! A significant performance gain for £150 Whereabouts you based? More than welcome to see what it's like (our specs are pretty similar) if you're ever up in the north
Cheers, Andrew

 

Didn't I see your car in a well known (locally) Elvington establishment ?

I need help as mine isn't fully well, but I need a 2.1 stroker for xmas

dunx

 

Do you think it would help with the T as well ?

 

you sure about that??????????

 

When there is no other underlying problem Dazza!

 

another vote for a harvey up-pipe with the gt spec headers.

made a massive difference to my sc46 turbo i run on my car.

i run non vvt heads (sti v4) my spool up in 1/2/3rd gears in better by around 200rpm ish in 4/5/6th is around 500rpm sooner.

mid range punch is massively different pulls mouch more strongly.

makes drivability very different with no difference in boost. i run 1.8 bar on one map and

my car will hold 1.8 bar in every gear till the red line (obviously i've never red lined 6th gear but holds to 1.8 bar every time i use 6th).

i know the subject was about turbo's but if you use one of harvey's pipes with any turbo you are going to see a massive difference.

 

when its proved the md321t is good for over 400bhp on a 2.0 sti and quicker spooling than a vf35 i will buy 1.........

 

has been proved time and time again, a 450bhp turbo is hardly going to spool faster than 350bhp turbo

 

The T is only good on a 2.0 if you have VVT heads otherwise i would leave well alone.

And even if you did have VVT heads the H would still make a better drivers car on a 2.0 (It's not all about bhp boys)

 

where is the evidence that a 321t is suited to a 2.0sti without lag lag lag....or even put your last 2 rolling rd figures up and prove me wrong.....
362bhp was it or am i

 

390 actually on a sick car as you well know. I have a boost plot on another MD thread here Dazza, take a gander @ it and tell me if it's laggy! I also have a Delta dash for 445bhp @ the time of mapping. You brag about your Delta dash figures so you can hardly question mine.

Just you stick to your diy reconditioned turbos and when you manage to make it last more than 5miles then come back.

 

362bhp on your first rr....then u took it 2 another rr for a second go...390 on a set of rollers that always read high.....cant rem ever bragging about my dd figures.
And i will keep going with my turbo project thanks........
.........only sayin what every-1 else is sayin........please no more insulting private pm`s thanks.
I was not convinced of the MD`s performance figure`s on a stock 2.0 sti m8 but if u want 2 make it personal that`s up 2 u.

 

sad.
I must apologise for the envious person ruining this thread!

BOT

 

 

I had ported headers when I first fitted the MD321H and I think the spool was very similar to a VF35 with non-ported headers. I struggled to make 400bhp with the ported headers though, so fitted GT Spec II and hit 402bhp.

I've got one of Harvey's GT Spec up-pipes waiting to go on, so I'll post my thoughts when it's on. Won't be a completly fair test though as also fitting Lateral turbo silicon hose and CDF light weight pulleys.

Anders

 

Just throwing in my 2 Pence. 785cc's are overkill. 650cc's will be well up to the job. Even going a bit beyond 400

 

were you running harveys gen3 up-pipe with his ported headers before fitting the gt specs

 

I was running a harvey up-pipe before the GT Specs, but not sure if it was gen1, 2 or 3.

Anders

 

Totally agree A 321H is one of the best turbos for a 2.0L road car aiming for the 400 mark as it responds so well. Mine made peak boost of 1.7 bar at around 3600 with AVCS heads and would hold boost right up the revs no problem.

321T will run more power up top, but won't spool as well, so arguably not quite as useable on the road. All depends how you like to use the gearbox of course