This'll test the fabricating skills

It's in , they're on ,let's hope

What a great day

After a few setbacks and a week of shite I wasn't feeling that good this morning when I set out to the rollers
Big thank you to Martin F , Keef and Peter at http://www.peter-burgess.com/

Car now runs like a dream .We had set the fueling pretty safe on the base map and it showed on the road and initial power run but by 2 oclock we were seeing real repeatable results and all this at a nice cool 12 psi .
About 20 odd runs with Martin and Peter talking tech and dialing in new parameters .
Here is the before and after plot .Good on the road as well so hoping to get it checked over and back to Darren very soon .I still can't face the carpet re-trim though ...Might add that to the list of things I don't do

7501 posts God I'm a gobshite innit

.
Pleasure Lee, no problem, nice solid result at the end of the day. Did several A-B-A tests, so we know the numbers were repeatable and solid, each change verified. The engine number in the table is prior to input of the measured transmission loses from the run down tests, so the final figure was 265hp as noted on the right for clarification.

Good day enjoyed it . Hopefully Darren will enjoy it too.

Result.


So how many PSI was the final run using? Was it with the chargecooler running or was that not deemed necessary in the chilly weather?

Thanks Lee. And thanks Martin for taking the time out to do this.

Alright I take the hint re the carpet

Speak to you tomorrow Lee!

All runs at 12 psi and it seemed really happy at that so we didn't push it any further .It's mapped up to 14 though so there is room for spiking .
Charge cooler running yes .Doesn't matter what the ambient temp is on the rollers as it soon gets heat soaked .This is where the CC does work well .It drops like a stone when switched on so I think we are getting good flow .Was a bit concerned running it through the old A/C pipes as they are quite different bores but all seems good

Nice work guys

.
Well out of curiosity and cross check ("should there be more in the can " type self questioning), and looking over old Renix map data with the power / torque results, the more I look at it and think that this RATS combo is pretty darn good for a street engine. This or similar could have been done so easily by the factory but they didn't, it's not silly powerful, yet it is colourful enough to bring out the character of the car. I think the balance of this build is in the turbo selection, and spot on for a Fast Car style approach. The exhaust A/R combined with the cam and otherwise OE kit, simply works. Comparing to Will's (old turbo setup) with a different turbo selection at 3000-3500 it's 100 lb-ft up, which for street motor is right where you want it. Sure Will's takes off from there, and there's no final comparison, but his application is hill climb competition. Then look at Mogster's recent OE run that is actually on spec for an OE setup, and you will see the difference. So I get back to what I was saying, why didn't they do it, as we are talking a change in cams and turbo only, the ecu is a map change on the OE Renix system, so really if tooled up from the start it wouldn't have been a cost adder? Pity... [/i]

why didn't they do it, as we are talking a change in cams and turbo only, the ecu is a map change on the OE Renix system, so really if tooled up from the start it wouldn't have been a cost adder?

I still come back to the argument that they simply didn't have to. Compared with other rival marques it was pretty much right on the money. I remember someone explaining what he'd seen IBM had in development for storage technology back in about 98 and it was miles ahead of anything available at the time, but they then reverse engineered it back to something with less capacity and speed - essentially what they thought the 'market could take'. We've now got the capacities and speeds that were in lab development back then, but they've only been out a few years. Gradual evolution to supply the market with what it wants.

I don't think it was as deliberate as that with Renault, but again the trade off was probably that it was as fast as the 944, 308, 300ZX etc so why bother.

These days it's Audi, Merc and BMW that have really started an arms race.

Anyway back to the GTA. If it ran a few more PSI (I know Lee had suggested 14 originally) do you think the top end would see gains? Lee said the boost was a bit unstable beyond 12 so opted for that.

I assume you mean the first gen 300ZX? I have a Z32 the same year as my A610 and it's very nearly as quick despite being far heavier. The engine is also a lot more 'driveable' despite being more powerful.

Seems to me the main strength of the 610 relative to other cars of the time is the handling/brakes, and the power is merely 'good enough'. I assumed the same was true of the GTA before that.

Darren,

Yes you are probably right, especially when you consider they were happy to strangle the cat versions and not really attempt to pull the performance back up. I still think it's a pity.

[quote=]Anyway back to the GTA. If it ran a few more PSI (I know Lee had suggested 14 originally) do you think the top end would see gains? Lee said the boost was a bit unstable beyond 12 so opted for that.[/quote]

You haven't driven it yet, smile, suggest you see how it goes and then look at it again in the future, possibly. If I’m not mistaken I think it's a 60 trim T3 compressor, so I would doubt that you would want to push that particular compressor further than 12 psi anyway. At 14 psi you will be dropping a far way down from the 70% efficiency band so just making heat and not making anymore power. If you wanted to go up from where you are now in terms of hp, then I would suggest you would be better off rethinking the turbo spec entirely. The compromise is the 0.48 A/R exhaust housing is only going to be good for a maximum of 280hp without generating excess back pressure and heat in the engine on this setup. A standard T3 49mm exducer turbine will be pretty much max'ed out at 300hp anyway (more normally see 280-ish as it's upper limit), so swapping to the 0.63 A/R on this combination is only going to yield a small gain in terms of peak power, but will lose a lot of mid-range torque and tractability - life is always a compromise. The particular combination Lee has put together for you is about as far as you would want to take it already. Hope that answers your question?

Cheers,
Martin

Thanks Martin. Makes sense. Nope I've not driven it yet!

Curiousity really - I only asked as Lee had originally suggested 14psi as the optimum and I was wondering whether that would have altered the power curve and upped the last section of it to give a more 'typical' curve.

Back to GTA turbos in general -
I think perhaps the other reason as to why they didn't develop it was merely that they got lazy and left the original config as it came out in 1986. They could have had multiple evolutions upping the turbo spec and cams and so on - these days you probably would see that, a la Impreza and Mitsubishi Evo.

But then was it enough of a sales success to justify it? Probably not.

.
Yes that would make sense, as my point of reference is the turbo outlet (as it is derived from the compressor map operating points), than at the manifold, as you are going to see about 1 psi drop across the OE intercooler, and 0.2-0.5max across the charge cooler. So it's in the right ball park.

As to finessing it a little more, yes possibly, but it would take either some road mapping time, or back on the rollers, ideally a combination of both. I known the region of the torque curve you are talking, I don't think you will see a huge difference though, and in terms of bang-per-buck, you've got all the good ones

.
Darren asked if I could help with improving the spool performance of his turbo, so from the faulksie parts bin I was able to put together a very reasonably priced replacement with an upgraded turbine to improve the spool performance…

So here goes, raw 0.48 A/R housing requiring modification for the waste gate port:



TomK’s (top shaft) and Darren’s (bottom shaft) balanced rotating assemblies side by side. Darren’s wasn’t looking for any more power, just increased transient response, so kept to a T3 Super 60 compressor with an new up-rated turbine; the exhaust housing being machined in the next steps to suit.



Oil cooled only core for a direct swap, but as I was later to find, he had the water cooling hardware in the car, difference is insignificant these days with full synthetic oils and frequent oil changes. I have test data that shows there is some advantage to water cooling to improve transient performance in terms of heat soak time-constant from the turbine assembly to the compressor, but for a road motor of this type of setup it isn’t significant. If however, you were talking a production 1ltr motor where the available torque is down to the last drop of turbo performance, then you are into a different game… oh a bit like the lethargic OE PRV / GTA turbo performance as supplied from Renault… laugh.. Fortunately Darren already has the RATs stage I package, so all good there..



Start mashing it together, mods to external waste gate housing to internal gated assembly along the way:







Final straight to completion…











Hey ho, all done bar waste gate setup:



Looking forward to seeing it on Darren and getting tested... but you do need to fit a boost gauge, and get a bleed valve if you want to take advantage of the potential than be stuck with 10psi..

Cheers,
Martin

As Martin knows, the car was initially running very well on the Weds night (Martin and I were in the LTH workshop till about midnight) but started to badly misfire about half way home.

I nursed it home from the M25 but it was clearly getting worse. Interestingly the only other real change (aside from the turbo) was a tweak to the mapping on the Renix to trim the fuelling a bit at idle.

So today I checked the spark plugs and they were extremely sooty. Martin's suggestion was to clean them off and regap to 0.6mm (from the standard 0.7) and swap back to the original chip, theory being that the carbon deposits were shorting them out.

So lots of scrubbing with switch cleaner and an old toothbrush to get them all cleaned up again. Dried them off, regapped and re-installed.

All seems better now but I'll be pulling one of the plugs again when I get a moment to check how they're looking. Hopefully this is just one of the trials and tribulations of late night ECU changes and not having time to get the lambda sensor bolted in to double check. (And to be honest the weather wasn't exactly what you'd want for trying to map a car - most of the roads had turned into lakes)

Big thanks to Martin again though for all his hard work, late nights and for building up the new (and much improved turbo)