Shaun

Everything was historically tested on the SPEC C first and then rolled out to the STI, hence why the MY03 SPEC C has the larger pipe and the MY04 STI didn't. Yet from MY05 onwards they both did.

I seriously wouldn't worry about it.

Semion

Twinscrolls are much better at the low revs, but slightly worse at the top. Singlescrolls are slightly better at the top of the rpms. That's why people got 360bhp on VF34 and no chance to get that power on VF36/37, imho. Anyway the key is the size of the turbo, no mods such as harder actuator spring, inlet pipe diameter enlargement can make your turbo produce more air, on overboost it just will work as a heater, causing a detonation. You could use race fuel or meth and then add some aggressive timing to get that 360bhp. But a car with the LM400 will be anyway faster and safier. Would it be faster on the aftermarket ecu? I found on this forum that people always got better results with the syvecs.

I just have known that LM450 is not a true twinscroll turbo, it's twin entry. It has two ports on the hot side in, and only one port (actuator shutter window) on the hot side out. Why did the Turbo Dynamics went that way, and what is the difference between twinscroll and twin entry housing design is interesting to me.

joz8968

iTrader: (13)

Re. Forge's actuators/springs:-

T3 actuator housing (the huge one w/large springs!)
blue = 12.5-17psi
red = 15-18psi

T2 actuator housing
blue = 14-18psi
red = 17.5-20psi

Bob Rawle

I don't agree that twin scrollers are delinquent at the top rpm range I managed to get 384 bhp from my MY03 car, std engine, std intercooler and injectors, my design exhaust and 80mm maf kit. Fuel pump of course and I did fit a stronger actuator (1 bar cracking) to the turbo. But it pulled all the way up, no det clean as a whistle. You need to pay attention to cam timing amongst other things but to say the VF36/37 will not go past 360bhp with the right supporting mods is incorrect. They will. Anything in excess of 1.3 bar boost at the top end will take you there.

360 bhp on a VF34 is something I would tend to challenge as well its not often that number comes up using pump fuel.

As Shaun states the OEM ecu is easily capable of looking after a 450 bhp spec car, if your guy could;t iron out that "VE" point (which is a common thing btw) then you should look elsewhere, its a maf scaling area.

RCM won't sell you a 80mm maf kit as its a BRD (me) product. If you need one then email me on rbr@brdevelopments.com and I will sort it for you. But since you are using the M800 you should not need a maf kit just a trumpet and filter which they do supply of course.

Strictly as long as an ecu is capable there should be no difference in performance properly mapped between two different makes.

Finally if you do want some other input to the car in mapping terms I will probably be visiting Russia at some point, a past customer of mine is native to your country and has a car which will need my attention, I know he will then be looking to involve a few others as well to build a group buy in Russia.

Finally ... Shaun "it" lives !!! Need to get it MOT'd and a couple of frills sorted at Forge then I will be on the boil. It has the LM500 billet with the large housing installed and I am very much looking forward to what that will bring.

cheers all

bob

joz8968

iTrader: (13)

lol

Although your TS will be a fair bit more spritely than my 20g (disregarding the power/weight difference).

Very impressed with the TS's "get up and go" -- as I have been out in APIDavid's previous JDM WR Blue Blob STi. Albeit he had an Owen's Development-fettled VF36 on there, producing about 391/395 IIRC. I was well enamoured by the low-mid range pick-up! Albeit the more linear response isn't quite so 'exciting' as a SS, IMO. Swings and roundabouts.

Shaun

To be fair the twinscroll for the GRP N use was for quick spool and pokey midrange.... which is what it delivered. It has always been accepted that the OEM TS exhaust housing is fairly small and chokes, which has always hampered outright power. If you speak to a turbo manufacturer you will get the same feedback. I know Bob (above) has had impressive results in the past with this OEM TS turbo (and to be fair mine were similar with my SPEC C, reaching around 370bhp back in 2005). However, I do believe these are exceptional results, rather than the norm..... something else we already know is what happens on car a, does not always follow to car b - even if they are identical.

IMO the mapper is more important that any ECU will ever be!

Yes the LM's are twin entry.... don't worry about it though. I have not seen one test with a comparison twinscroll that gives me any evidence that the twinscroll gives quicker spool or lowdown power and torque.

The fact is the LM's work.... period!

Shaun

Awesome news Bob.... it will be interesting to hear of how it all works together, once you're able to turn the wick up!

Based on the conversations we've had before and the experience I had with my previous SPEC C..... You best make sure your insurance policies are up to date! You're going to love that torque!!!!

Impreza sti jdm

Bob is there any chance or have you planned any trip to Malta?as it would have been much better if the car was mapped by you.Also as we're on the mapping subject,as i have a version 7 ecu(af481) on a version 8 sti jdm will this make any difference to the car?The only thing i can say is that the car works perfectly but due to it being fitted with an unequal 4in1 manifold it used to give 0.75 bar at 3700rpm in 4th gear and max boost is 1.1 bar. with afr of 11.7-12.2 on wot.Now i have removed the engine as the clutch was slipping a bit and already bought an exedy stage 1 clutch kit but now im not sure if i should buy an aftermarket lightweight flywheel or just resurface mu current one as i've heard many negative things about the juddering that lightweight flywheels give.

About the actuator do you know which one you had installed on your turbo?And if so do you know what is the spring colour(blue or red) on a forge actuator unit that is 1 bar crack pressure?many thanks

joz8968

iTrader: (13)

Post #783 ^^^

Blue covers it.

Impreza sti jdm

What will be the difference if i buy the red spring instead?i assume it will hold more boost,Im looking to be running approx 1.65 bar(circa 24.3psi) of boost.

Shaun

The stronger the spring the less duty cycle required and the more chance you have of achieving higher boost levels at the top end of the rev range. It also means that the minimum amount of boost you can run is dictated by the crack pressure.

You have no chance of holding that boost on the OEM turbo!

Impreza sti jdm

Oh ic shaun,In your experience what do you think is the best spring to choose for the vf37 running the already specified 1.65bar?thanks

rickya

iTrader: (18)

Blue spring, you can hit peak 1.7bar on a Vf36 but wont hold anywhere near that for any length of time. I wouldnt worry too much at this point, it will make the boost it will make which depends on car itself and mapper.

Shaun

Agreed.

johnfelstead

You can hit over 2.1 BAR with a VF36/37, I saw it on my own car when we did the initial mapping on my 2.1. My VF37 runs 1.8BAR mid range (400lbft@3500rpm), but it's down to 1.1 BAR by 6Krpm on my 2.1 litre, so only produces 355BHP, as seen on the conservative end of the scale Zen rollers last year.

rickya

iTrader: (18)

John do you think a std 2.0 litre (non stroker) could make that kind of boost?

ps Also a bit off topic but what is the exact spec of your 2.1 stroker build? If you dont want to post here could you pm me. Many Thanks

johnfelstead

I would think it could get close to that on a 2.0.

The 2.1 i built myself, base of the engine is a stock MY05 JDM STi.

heads were skimmed 0.003", block skimmed 0.005", bore 92.5mm, stroke 79mm factory 2.5 crank, pistons Mahle 2618 to a bespoke design by SMG for a 9.1:1 CR when used with cosworth 93mm 1.1mm head gaskets, piston clearance 0.0035", Manley steel H beam rods with ARP bolts, ARP 11mm head stud kit, ACL race series bearings, supertec valve stem oil seals, standard oil pump with polished regulator plunger, AP racing friction plate in stock cover, group N engine mounts, super pro billet alloy pitch stopper, heads were stripped and cleaned, no porting work. Stock injectors, inlet, airbox, high flow filter, miltek 3" decat, walbro 255, stock VF37.

Pistons are good for 700BHP, rods are suposed to take 650 BHP but i'd limit it to about 550 BHP based on advice, reason to change rods from stock was to allow an 8krpm limit on the longer stroke, not needed if dropping rpm limit to 7.5K at this power level. Only down side is the pistons are a bit noisier than stock, which you tend to find with the high expansion 2618 material, but they should take any abuse i throw at them.

road dyno shows it as 368BHP@5600rpm, 416lbft@4097rpm on V-Power, Zen rollers shows it as 354BHP@5700rpm, 400lbft@3550rpm with a splash of race fuel mixed with V-Power. Zen rollers loaded it up more than on the road, it was mapped for the road, so the peak torque shows earlier and the power curve wasn't as nice as i see on the road, it pulled a bit of timing out on the rollers.

4th gear acceleration with the car weighing 1575kg on V-Power
40-60mph 2.1s
50-70mpm 2.1s
60-80mph 2.3s
70-90mph 2.6s
80-100mph 3.3s

This setup is no good for top end power, it's the complete oposite of what shaun has done to date, engine response is more like a groupN car than a race car, turbo gives great response but revs are not what you want, i change up at 6krpm so in reality never see the last two speed ranges in 4th, i'd be in 5th at that point. I think with a bigger twin scroll turbo it would be superb but it would sacrifice the ability to cruise then just boot it if needed, you would have to drop a gear to get the same acceleration.

Engine is overspecced for the rest of the setup, but i will be having a play with that shortly to see which setup i prefer.

rickya

iTrader: (18)

Thanks that is just the type of info I was hoping for, in fact the deatil is more than I was excpecting!

pm sent

JTinnovations

iTrader: (2)

Just to echo John's information, the VF36 on my JDM 2.0 produced about 1.7bar peak, tailing to 1.0 bar. Tried uprated actuator and it didn't really make any difference tbh. 340bhp/380ftlb.





Very similar power/torque when I ran this turbo on the 2.5l as well.

Bob Rawle

That got a bit hot by the look of it Tim did you still have your top mount then ?

I used an uprated actuator from Turbo Dynamics, set to "crack at 1.1 bar. Making boost at the outset is never a problem holding decent boost at higher rpm's always as the back end of the VF36/37 is too small really and the turbo cannot keep up. My car held around 1.28 bar in the end, if you can get over 1.2 at the top then you are onto more than 360 bhp.

Malta ... yes I do visit I've been over three or four times now so happy to. Do you know Josef? Blue WRX with 2.1 stroker he recently ran a storm in Sicily at the track day there coming first. If not let me have your email and I will give you his contact details. He is looking to arrange the next visit.

cheers

bob

JTinnovations

iTrader: (2)

Yes, that was on the old engine and before the big spend started!

IIRC there was a fault found afterwards, but I can't remember what - a leaky pipe perhaps. That run was on a RR day rather than a mapping session.

Impreza sti jdm

Oh yes i know who he is,blue wrx with lotx of stickers heh.That's awesome i already sent him a msg on his facebook.Thanks alot.

I still dont know if i should go the lm450 route or keep the vf37 as i would like to keep the stock tmic as im in love with it heh.Im definatly not considering going for a lm400 as said in previous posts.

Shaun as you have both experienced extensively the lm450 and the vf37,lets take for example a quarter mile drag race,will the lm450 leave the vf37 for death or there isnt much in it?And what about a trackday?thanks

Shaun

The information that John has put up is very useful. I'm especially drawn to John's acceleration times in-gear.

John's times 1575kgs 2.1ltr, VF turbo:
40-60mph 2.1s
50-70mph 2.1s
60-80mph 2.3s
70-90mph 2.6s
80-100mph 3.3s

2ltr JDM, LM450 - My car
40-60mph 2.3s
50-70mph 1.9s
60-80mph 1.8s
70-90mph 2.0s
80-100mph 2.3s

In the real world this indicates how great the LM450 works on the 2ltr. Had mine been a 2.1ltr, I wonder how the above would of changed in my favour (40-60mph)?!

What the LM450 achieves on a 2ltr is nothing short of outstanding in my book. A few years ago you would of never thought that the kind of driveability and performance was achievable on the 2ltr at this power level.

Impreza sti jdm,
In both of those disciplines the LM450 would be all over a VF37 equipped car (all other things being equal) imo. From my personal perspective, there is no comparison between the two.

Impreza sti jdm

I see,So there is no contest in other words.Shaun regarding the Lm450 turbo,i've visited litchfield website and noticed that there are a list of turbo options like race turbo fitting kit,76mm Ported Shroud Compressor Cover,Race Bronze bearing carrier,Garrett Speedsensor and Full Turbo blue printing.What are these all about and do you have all of these fitted to your car?and what do you think of the above is essential?and in other words what is the full spec required for such(lm450) swap?,cosidering i already have the tomei twinscroll header+milltek twinscroll decat full exhaust.I would have liked to keep the stock tmic but as i've seen in your posts it might hold power a bit.Many thanks and sorry about all of these questions but you seems to be the right person to ask.

Shaun

My Billet LM450 has:
58mm inlet - no need for the bigger inlet imo.
Race Turbo Fitting Kit - all the appropriate fittings.
Race Bronze Bearing - upgrade to bearing for longevity and optimum spool.

The above Spec will be fine.

Someone else on here used the Tomei twinscroll headers. They were not very good and he went back to OEM headers which gave better spool-up.

To get the best out of this turbo you will need to junk the OEM TMIC imo.

JTinnovations

iTrader: (2)

That was me...but it was on a 2.5l not 2.0l, and I think the pipe diameters weren't best suited for the 2.5. I would not change oem for tomei, but if you're doing a single-to-twin scroll conversion they're probably fine. And I believe they now have a version designed for the 2.5l

TimH.

Impreza sti jdm

Yes,thats what i think as well but i think for the lower powered twinscrolls (circa 400bhp and on a 2ltr) the tomei ones might actually be good as the oem one if not a bit better on spooling.I would have prefered to get hold of the stock header but i couldnt find any and the most ironic thing is that the previous owner had "littered" the oem header.

Till i get enough money to afford the whole lm450 conversion i decided to keep the vf37 till i find someone that wants it and in the mean time i will fit the uprated actuator with the red spring(for a 1.1 bar crack as Bob Rawle's one) and have the wastegate ported a little.And by doing so at least i will get to see the full potential of the vf37,as till know i guess i havent even saw 60% of its potential.thanks.

johnfelstead

Road dyno 4th gear runs doesnt really show the full picture in terms of how the full package works or how the car accelerates through the gears, for example even on my old 2.0 the car would do 40-60 in 1.6s in 3rd gear, which is 0.5s faster than doing a 4th gear pull on my 2.1.

One test i would like to see you do shaun, is an acceleration run from 1st gear at 3000rpm (so launching isnt being factored) to the redline in 4th, i bet it would be interesting to compare to mine.

Shaun

Granted... it doesn't show the full picture, but it shows more of a picture than comparing dyno graphs!

Will look at doing the test you describe, although gear changes will play a fairly big part in that, so not conclusive using a different driver imo.

johnfelstead

I'm not a slam the thing forcing the syncros type of driver, so i would think the gear changes would be very similar. Easy enough to counter act anyway looking at the traces.

Just start a logging session and log the main parameters, we can then compare the traces.