My GTA Turbo Project

Yes it would probably on a dry grippy surface and a peak torque start.. but the likelihood is Jon won't be treating it that harshly. As you highlighted before the couplers are available uprated, please post the link again, I can't remember where you posted that now sorry. As to 5th, same again, don't try a peak torque pull in 5th, do all that work in 4th, and tickle along in 5th. I think he will be fine, besides he has a soft start with his clutch at the moment being the weak link

Glad the cams ‘n’ things worked out good – Faulksie inside . Don't push the boost if you're getting oil introduced to the chamber if it's there... have you checked the turbo oil drains are not flooding?

http://www.delorean-parts.com/Merchant2 ... gory_Code=

Easy to say "don't floor it in 5th" but we all do it on the motorway when you want to get a wriggle on just to close that gap, or go for the exit etc. Just sayin' What's an A610 clutch go for these days?

Rich took his car because I was about to move house. I'm sure I'll see it again soon enough. The turbo drain is fine - in fact the only suspect item apart from one of the rebuilt turbos is the state of the stem seals in one of the heads.... which would make sense, don't ask me how I know....

That's where my two stage turbosmart comes in- 17psi for daily use so as to have fun but not kill the clutch or box then much higher for the faster stuff. It works well- enjoyable every day without the worry and fuel cost but amazing power when you want it

What boost was it running to make 350bhp?

What boost was it running to make 350bhp?

Good question, what would you evaluate it to be Tony out of interest?

Its a hard one to gauge but I bet it will be less than I think :0). Original engine (internally standard) but with fueling and intercooling sorted used to make 240-250 bhp at 1.1 bar. My 3 litre makes about 315-320 at 1.1 bar with a T38 blower. The most efficient turbo engines make about 140-150 per litre at a bar of boost (with a sensibly sized turbo). So my logic is going to say your cams and other mods have improved volumetric efficiency by say 15-20% so I'm going to guess about 1.7 bar or thereabouts to net 350bhp. It would be interesting to get another GTA on those rollers for a comparative figure though or a 1/4 mile terminal speed. Don't like to be sceptical but figures vary so much from RR to RR. A friend of mine has a MK 1 Escort with an Atmo Cossie tuned to the hilt and he has seen 40bhp difference (220-260bhp) on different rollers. An exceptional result regardless :0).

Very good Tony!!!

Holding 22 psi peak at 23/4

Martin, Jon love the video on the dyno.

Well JV's car is with me to have the Renix ecu setup with his new build as above, and initially it didn't want to behave... I couldn't understand why I needed less and less fuelling compared his old map, when I was expecting the opposite given some extra flow and fresh engine...

So it was time to investigate.. plug colour indicated that it was in fact running lean, which was the opposite of what my wide band O2 sensor was telling me, and you can get pulled into believing the number... It seemed to calibrate in free air ok, speed of response is hard to compare over time. Looking deeper I found oil in the inlet, and so went back to the turbo... found the source of the oil and some other interesting things, noting this was a recently professionally (turbo specialists) rebuilt item...

The turbine is white - lean, the divider bridge in the collector is badly cracked and white, yet the rest of the collector is black, and the worst was the waste-gate housing that is cracked right to the outside world. Indeed, the most surprising thing for a unit supplied new to Jon, is it has a weld repaired turbine housing that has subsequently cracked and started degrading since... Quality!

Oil and silicone (coolant) contamination in exhaust is death to Lambda sensors and degrades them quickly, so likely my false readings are down to a now defunct sensor… So a word to the wise, before incurring costly mistakes - check before you put your probe in!

All Garrett turbine housings crack across the wastegate port. Turbo rebuilders don't even replace them because its not actually an issue unless it spreads across to the turbine wheel (not that you can buy a new T3 turbine housing anyway)

http://www.uksaabs.co.uk/UKS/viewtopic.php?f=3&t=103799

And seeing as Garrett havent made any T3 housings, let alone ones with the Renault specific circular cutout in the flange for over 20 years, you can see how old even recon housings are.

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Come on David, get up to speed, that was yonks ago... No that one was truely cream crackered, and some artist had a go at welding it up which was quite funny as it was cracking out in lumps. This one was breaking up, and cracked right through, yep what you say about the waste gate hole is well known and wasn't my concern, the rest of it breaking up was.. the housing is also designed to provide containment if the turbine were to let go, and this one wasn't going to do much in that way, I know I wouldn't want my head by it... Still got it if you wish to give it a try

Honestly, Ive seen worse than that, and it will never 'let go' because the 5 bolt wastegate housing holds it all together. Will leak gasses though.

It would be worst on the superior Cosworth / Lotus style housings which don't have a 5 bolt wastegate flange, but a 2.5" downpipe outlet and wastegate integral to the turbine housing.

What can be said though, is looking at the dyno plot and the boost pressure involved, that its the final nail in the coffin for the argument that the manifolds / link pipes / turbo setup truely suffocate the PRV.

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Interestingly this was cracked into the turbine snail, so if it had gone it would have just come straight out there. I've got the Cossie housing on my 16V Integrate engine, so know it well.. my down pipe is also welded to it lol!

Yep everything is a restriction at some point. I have EGT and turbine back-pressure ports welded in now on JVs , so will be able to measure directly and get the data, and that will speak for itself no doubt. Have you got any values to compare on a similar setup as reference? I should be back on the same rolling road soon to do some final tweaks and will get the measurements then. I can also do in-cylinder pressure measurement if I get time to setup on the day, but most of what I want to do is the transient pickup / throttle response than wot full power. If Dave Miles is up for it we could run them back to back on the same day, be interesting..

Cheers,
Martin

Maybe Martin, when you thinking about it?

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Interestingly this was cracked into the turbine snail, so if it had gone it would have just come straight out there. I've got the Cossie housing on my 16V Integrate engine, so know it well.. my down pipe is also welded to it lol!

Yep everything is a restriction at some point. I have EGT and turbine back-pressure ports welded in now on JVs , so will be able to measure directly and get the data, and that will speak for itself no doubt. Have you got any values to compare on a similar setup as reference? I should be back on the same rolling road soon to do some final tweaks and will get the measurements then. I can also do in-cylinder pressure measurement if I get time to setup on the day, but most of what I want to do is the transient pickup / throttle response than wot full power. If Dave Miles is up for it we could run them back to back on the same day, be interesting..

Cheers,
Martin

You don't even need to do that. You can see from the torque graph, torque graph is a great indicator of breathing. Its an identical plot to how Politechic did on their 270 degree cammed GTA, made peak torque at 4250, peak power at 5100.

The problem is is, doesnt matter what you do with cams on this engine, the manifolds will make it not rev any higher, so the car isnt actually breathing any better.. A standard car makes peak power at 5750, and every tuned GTA, cammed/headwork or not, never makes its peak power above 5500. Never seen it in all the cars done. Yet a Atmo GTA, will rev round to 7k or more depending on the cams.

So you have to weight up, what have the cams gained? On Jons plot, the car is running 23psi, but makes less torque than a standard GTA running 10 psi at 2500rpm-3000rpm, and even the peak torque is lower than the 380lb/ft we have seen on a mapped but non cammed GTA at 14psi, verses Jons 360lb/ft, but needing 23psi to do it.

Id put money on if you ran Jons car at 14psi, it would be at the 300bhp level, but the problem is it will have less peak torque and less low down torque too than a non cammed GTA. Without opening up the manifold side, all it does is narrow the powerband to 4000-5000 instead of 2500-5000, and the extra power has been made due to running 9psi boost more than other cars, which is a significant increase in boost.

I bet Jons car feels alot like my Porsche looking at the plot (apart from the limitiation of revs), a smooth build in power, without that traditional kick at low revs.

Ill dig out the Politecnic map, its nigh on identical.

http://www.youtube.com/watch?v=qkiix0aveRk

Just an observation ...it makes me feels very similar

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Dave G, yes all data is good, do need to make sure we are comparing apples to apples, and best that numbers discussed are referenced ie let's stick to wheel numbers than any supposition of any crank figures, and 2.5 ltr swept capacity, 12V. Also the wheel plot for the 280lb/ft 14 psi 2.5ltr would be good to see, as you say the torque curve pretty much follows the volumetric efficiency provided all points have been optimised - all good learning. Please post them up.

Absolutely the OE headers are a restriction, I don't think anyone has ever said otherwise. Indeed, I didn't make any categorical statements about the brick wall being 300hp etc etc as you have in the past, I've just said they are not idea from many aspects, but from the point of view of squeezing out 350hp they are still there on Jon's engine, they haven't melted, cracked or collapsed. In fact we weren't actually trying to hit any number on the day for the sake of it. Now subsequent to that day, and having setup the mid-range and got that where it needs to be -within the limits of reasonable tuning time and repeatability (and not to mention that this is on a DS501 Renix 1 ecu not an aftermarket or later Renix ph2 or a Fenix 3A / 3B unit - which is no small point on it's own), then I'll be back on the RR and will take EGT and back pressure and see where we go from there.

I think in terms of the UK GTA / PRV scene, then we should be working hard to move technology on as a community, otherwise Germany / France will continue to been seen as the only ones with higher performance offerings in their clubs. So the more cars with better performance than OE what ever the levels is a good thing in my book. 350hp is still 350hp, and Jon is having a great deal of fun with it on the road.

Now to the example of running at 14 psi, sure will do, happy to oblige and will get that number when I'm on the RR next with Jon's car - good bad or indifferent. Further, I can make a better comparison, I have a 2.5 ltr swept volume block, with 3ltr heads - so same as Dave Miles in terms of port and valve arrangement, except obviously not 3ltr. I'm running the A610 / Bi-Saf cam profile, so that is a direct match, 3ltr n/a inlet manifold, and this is running OE 2.5ltr turbo headers with a single turbo. We can factor the capacity increase &/ or normalise the results to per cc, so we are then looking at the bi-turbo configuration with superior headers over the OE headers and single turbo. This then should drive some data behind the merits or not of the different arrangements.

Cheers,
Martin