ClintUK

97UK car

In no way am I a turbo expert, but I wanted to change my standard turbo TD04L 13T before my Apexi remap as I wanted more than 265 / 270bhp that this seems limited too.

I had a plan, but it went wrong and i ended up with a different spec, that is TD04L 19T So standard exhaust wheel with a larger 19T compressor.

During mapping we experienced a lot of surging, but upping the boost solenoid duty cycle eliminated most of this.

1.3 bar can be held across the rev range but spool / low down torque is disappointing.

I have wide throat sports cat down pipe and ported OEM headers. Fuel pressure is now 3.5 bar.



Can anyone give me any ideas what's gone wrong ? I'm disappointed in the lack of torque lower down and the uneven torque curve tells me something is not right.

Many thanks for any comments.
Clint

dowser

Surge will occur as the turbo is spooling, you'd normal reduce solenoid duties to slow spool until past the surge point. This could also explain the disappointing low down torque. Do you have an overlay showing boost? Who did the turbo? Was the exhaust wheel cut back too?

Richard

ClintUK

Exhaust wheel standard, although the exhaust housing is flowed on the inlet.

I don't have a boost map overlay (may be able to get one from my maper), but I know it doesn't hit 1bar till about 3200rpm.

What benefits does clipping the exhaust wheel have and what about incresing the size of the exhaust wheel i.e. moving up to the TD04HL wheel which is 52mm rather than 46.8mm.

I'd rather not say who did the turbo just yet as I'm hoping he'll do the right thing and help get over this - I think I've been used as an experiment to be honest and I only used him as the machine shops in my area did not seem up to turbo work, otherwise I'd have a different spec turbo completely DIY and who knows (other problems :-) ?

dowser

Only experience I have with TD04 is fitting KKK compressor wheels. But it is normal to 'clip' the exhaust wheel (cut back 6-7 degrees off outside edge of wheel) to balance things better when fitting a larger compressor wheel.

When done right it can turn the TD04 into a very nice 300 HP capable turbo. Edited to add: it is *very* trial and error though....I'd try the clipped exhaust wheel first

Richard

ClintUK

Can you explain how clipping the exhaust wheel works.

I really need to go back to Uni and attend some lectures :-)

A nice 300bhp turbo is what I'm after, but with more torque low down.

DIY - pain in the **** - wish I earnt more.

dowser

Draw an imaginary line across the outside edge of the exhaust blades, it will be angled downwards. Using the top centre as the pivot, move the line 6-7 degrees downwards. Trim the blades this much.

You'll need a lathe and should also rebalance the whole assembly afterwards. It is a machine shop job.

ClintUK

Sorry Richard I knew what was involved, but removing the surface area from the wheel surely reduces spool and just allows more gas through at higher pressure.

So why would clipping be a better option than going for a larger turbine ?

I hear the HL turbine is good enough to spool as low as 2500 rpm, which I'd be happy with considering what I have at the moment.

Jolly Green Monster

iTrader: (4)

that and what sounds like the exhaust wheel touching!!!

Lowing the duty made it worse.. ie. it was kept in the spooling area longer..
increasing the duty and it spooled quicker and the surge was not as bad..

Simon

dowser

My understanding is that without clipping, fitting a larger compressor wheel means surge is more likely to occur (as all exhaust gases power the exhaust wheel). Clipping reduces the amount of energy transferred to compressor wheel.

The above assumes 'surge' is the inability of the compressor wheel to drag enough air into the compressor cover.

I'd still try clipping the exhaust wheel - never heard of anyone fitting a larger compressor wheel without clipping exhaust wheel, I can imagine factory tolerances on an OE turbo means not clipping is guaranteed to give mis-match issues?

My mechanic always used 6-7 degrees - worked on his TD04 hybrids and the TD05/06's he machined for me.

Richard

ClintUK

Thanks for that Richard.

Since I've been looking all over for info on whats going on here I just have to share this with you :

The people I have talked to generally think that a "big" compressor with a "small" turbine is somehow ideal. They tend to see them as separate entities. They like to think that a big compressor will give them the ability to make "lots of boost", while the small turbine will let them "spool it up quickly". The problem, as most find out, is that one of two things happens... 1. The small turbine powers the bigass compressor straight up into surge... or 2. They can't make any power up top (and the turbo is "laggy" in certain regions of the powerband and during some transients).

This by a chap called Fernando from Barbados

dowser

And that's the flip side and the second reason for clipping (that I conveniently forgot ) - reduce EGBP at higher revs.

Seriously - clip the damned thing and I'm sure it'll be fine. What you lose in response (from removing some exhaust wheel fin) will be made up for with the bigger compressor.

Try talking to Andy.F - he offers an 04 hybrid, and I'm sure he did extensive research on the best match.....he'll be happy to sell you one

ClintUK

Rich, if I had £600 I'd have got one of Andy's to start with

And the most annoying bit is that this isn't the spec I wanted

Going to buy a ticket for tonight and sell out to the devil

Bob DeVere

ClintUK,
Greetings. I Googled TD04HL-19T and came across your conversation with Dowser. I'm upgrading my turbos (95 3000GT VR-4) and I'm considering this particular turbo, based in part on Jeff Lucius' excellent web page for Stealth/VR-4 owners. It sounds, from this post, as if you were not very satisfied with your purchase. Have you changed your mind? Would you recommend against this turbo?
Bob

ClintUK

Bloody hell Bob - this threads been dead ages.

What I wasn't impressed with was the TD04L 19T the compressor was too big for the turbine and I had AWFUL surge.

I ended up with T04HL 19T and it's a cracker, 305bhp and 310ftlbs on 2L engine at 1.3 bar. I don't get surge and torque is much better throughout the rev range.

It might benefit from having clipped turbine to improve top end flow, but I don't have the will to try after my 'journey' There is the option of the TD04H turbine which has smaller turbine blades to start with.

How it'll work on your 3000GT I have no idea, but if a single one can flow 300will 2 do 600bhp with more boost? Could be fun

Just to let you know, my mapper thought the limiting factor was my standard TMIC. Reckons he could have got 1.35 - 1.4bar out of the turbo, but IC and exhaust starting to limit things.

Best of luck

Bob DeVere

ClintUK,
Thanks for the info. There are a couple of good forums over here for Stealth/3000GT, but relatively few have chosen the 19T turbos. They are a little more pricey than the 15G and others more commonly used, but if I read the turbo map correctly (always a question) then they are almost perfectly suited to my engine. I've spent a lot of money (wisely, he hopes) on engine rebuild to support the higher boost, and I'm ready now to do the fuel, ECU, injectors and turbos and to start to have some real fun. One of my sources is Dynamic Racing, run by Matt Monnet, who drag races this heavy beast and gets mid 9's even so. He has a lot of credibility in our community because of it, but he knows that isn't my objective. I'm strictly a street driver, but I do love the rush. He offers a 19T upgrade, but he's one of the few. He also offers a choice between TD04H and TD04L, saying the "L" spools faster. That's what I'm opting for. I hope I don't revisit your problems with lag and surge. I'd hate to spend all this money and find it undrivable. My fingers are crossed. Thanks for taking the time to reply.
Bob

ClintUK

Hi Bob

I really can't say how the TD04L /HL 19T will work on the 300GT as the 3L V6 will give a completely different result.

Matt obviously knows what he is on about so can't see you going wrong there.

Just a quick thought about it - the single TD04L 19T on a 2L engine doesn't work as I found out. Too much exhaust for the turbine to cope with. However your application is basically 1 on a 1.5L engine. 25% less volume to flow per turbo. Difference in the L to HL turbines is 23% area which makes it pretty even, so sounds like the choice for you for spooling up.

Used to think about having a 3000GT myself, but the boss said I had to have 4 doors - Best of luck