Sydneykid

Hi Mike, seen it a couple of times, happens because when the turbos are high flowed they don't enlarge the wastegate sufficiently. My suggestion would be to take them back to the turbo shop and have them upgrade the wastegates.

Hi Tom, I know Greg, but not very well, he travels in higher circles than me. If I remember rightly I spoke to him a few times when he was the Ralt agent for Formula Atlantic/Pacific. I was at Calder when Nelson drove the Formula A/P for Greg, plus I saw Roberto Moreno drive as well. Circuit racing people tend to be a bit insular and stay within their our team, plus he looks after a competing team now. The main issue is whether or not we will have any more production car racing, that's a bit of a focus right now. As for "who is we", well a couple of years ago, on another forum, I told everybody who we is, and I got driven crazy by phone calls with people asking/begging for work to be done. We are a race team, we don't do any retail work, we don't have anything to sell. So it is of no benefit for people to know "who we is".

Scrubbing out? That's more of a term I would apply to poor wheel alignment, not different size tyres on a 4wd. Having different diameter tyres on a Stagea will not scrub out tyres, but it will accelerate wear on the ATTESSA 4wd clutches. Basically what you are looking for is the same rolling diameter of tyres, so; 245/40/17 205/55/16 225/50/16 225/45/17 245/45/16 all have basically the same rolling diameter ~630 mm An example, if you have say 7.5 X 17 on the front, then 225/45/17 would be OK with 8.5 X 17 on the rear with 245/40/17. You need to check with your tyre supplier, as diameters vary between brands. Hope that helps

What's your power target? What boost? I have a T51 56 trim compressor map and a T04 54 trim, but no T51 54, if you have the correct compressor map I can easily work out max power and boost. That will give an exact result. In the interim, looking at the T51 56 and T04S 54, it looks to be around 47 lbs of air per minute at 1.6 bar. Good for ~500 bhp 47 / 23.5 * 19 = 38 mm wastegate. So if you power target is 500 bhp with your engine specs and you can run 1.6 bar, then 38 mm is what the formula suggest would be the ideal size. Hope that is of some help

OK lets start off with the theoretical stuff, posted some time ago....... 1. The wastegate size is relevant to how much horsepower you are targeting 2. If you want to run high boost, then a smaller wastegate is better than a larger wastegate. The idea being that in order to generate high boost you need most of the exhaust gas going through the turbine, not through the wastegate. 3. If you want to run low boost then a larger wastegate is better than a smaller wastegate. The idea being that in order to keep the boost low you need a lot of the exhaust gas going through the wastegate not through the turbine. But what is high boost? Well for the sake of this discussion I have settled on 1.2 to 1.4 bar (18 to 21 psi) as being the divider, thus 1. 2 bar and under is low and 1.4 bar and above is high. How did I arrive at this number? Well based on the results of the surveys, this seems to be the most common point where the wastegate sizes change from theory 2 to theory 3 (above). The next bit of theory is that it takes 1 lb per minute of airflow to make 11 bhp in a current generation 4 valve engine. This is a pretty well established piece of turbo sizing philosophy. But how do we relate this to wastegate sizing? Well referring to the results of the surveys, it seems a straight 1 to 1 relationship is not too far from the average, so 1 lb of airflow = 1 mm of wastegate diameter. What I am trying to do with the formula is give a baseline, something to think about. An 85% fit type of thing. At the moment there seems to be a majority of guys wanting external wastegates who don't even know where to start. They have been told for big horsepower you need a big wastegate, which is not necessarily true. They have been told you can't have too big a wastegate, which is definitely not true. They have been told for high boost you need a big wastegate, which again is not necessarily true. In order to do this there is one main assumption, that the turbo is pretty much the optimium size for the target power and boost. If it is totally wrong then whether the wastegate is sized correctly or not is really irrelevant. The turbo / engine mismatch is gunna kill horsepower / response anyway. A a 50mm wastegate valve is going to weigh twice as much as a 35 mm one. So there is an inertia issue to be considered. I think that is really the crux of the problem. The diaphram has to move twice as much weight, in and out very rapidly. This has 2 undersirable effects incomparison to a smaller (more correctly) sized wastegate. Firstly the too large a wastegate has to open and close more often, as it has too little exhaust flow when closed and too much exhaust flow when open. This wears the diaphram, due to the requirement for more movements and more weight. Secondly all this opening and closing of the wastegate affects the amount of exhaust flow though the turbine, this leads to fluctuations in the boost control. eg; I have seen a relatively low powered engine, with a very large wastegate, move up and down 0.3 bar in its boost as the boost control circuit struggles to keep up with this open, closed, open, closed requirement. ---------------------------------------------------------------------------- Enough theory down to the practifcal stuff; As many will remember I got 40+ guys on this forum to fill out a few simple questions on their car. I then compared what the formula came up with for the wastegate size and what their car actually had. In 35 out of the 40 cars, the formula came up with the same wastegate sizes as they had. In 2 cases it was one size different, but when I checked these 2 further out I found that the guys had actually told the wastegate supplier that they wanted to run more boost than they actually were. So the formula was right, they just had the wrong size wastegate. In one case they guy had moved down a size in turbo after a failure. Now these wastegates had been specified by a number of well known turbo experts from GCG, Peter Hall, CAPA etc locally or had come in kits from HKS or Trust. Better still the guys seemd pretty happy with the results. This was all done over 18 months ago and since then I have used the formula to select 5 or 6 wastegates. I have been very happy with the results, as have the drivers. Good horsepower and good response, why wouldn't we be. Enough for now

Yes, very worthwhile Yes, not a problem.

Are we talking camshaft timing? If so, the +2 inlet -4 exhaust is a place to start if you are running standard cams. I have seen some different timing work better with large duration cams. I have a pair of Jun 272/280's with 10.5 mm lift going in my new RB31DET, so I will be most interested in where the timing ends up for best average power using those.

Nah, #5 and #6 are different to clear the master cylinders, brake and clutch. As you can see they are the same close to the cylinder head, so you can cut and weld on a flange.

That was a top notch post TG. As yoyu can see above, I have picked out a couple of things I would like to comment on; Fuel economy is important in Endurance Racing, we worked very hard to save one stop at Bathurst, it was a race winner for another team. Quite few race teams have both engine and chassis dynos, we actually have 3. One engine, 1 roller and 1 hub. Porsche racing is class based on power at the wheels. They have a portable dyno and they regularly and randomly stick cars on the dyno to check their power. Race teams use the engine dyno a lot more because it is very expensive to rebuild race gearboxes, diffs etc. They are all lifed and wearing them out on the chassis dyno (at $10K plus per rebuild) is not very smart. I should point out that we get just as consistent results from the chassis dyno as we do from the engine dyno. They are both run by the same engineer, he calibrates them exactly the same each time, goes through the same set up procedure each time and they live in airconditioned rooms. If an engine has 15 bhp more on the engine dyno, it will have 15 bhp more on the chassis dyno. When we have raced away from home and need to check a problem (ie; Philip Island last year) we have borrowed another (local) workshop's dyno (same brand). Our engineer goes through his calibration and setup procedure and produces the same result, give or take a bit of weather effect (non airconditioned dyno room). My suggestion (as always) is to build up a relationship with your dyno tuner, that way it is in his best interests to give you repeatable results.

Well, well, whadyaknow, here was me thinking this guy is crazy. You are going to have some strange tuning issues to overcome though.

If it flows more than 45 lbs of air per minute, then it isn't a 450 bhp turbo.

Keeping the same diameter front and rear is correct, but width is irrelevant.

Not compared to wife, children and house. :wavey:

My rule of thumb is 450 bhp (270rwkw), over that and I tend to do everything. This is because I just hate pulling RB engines out of Skylines, so I only like to do it once per car. So many guys have problems with pistons at or over that 250 rwkw mark, you can usually pin it down to tuning, but sometimes it's bad maintenance. Some might call it bad luck, but you really make you own luck as far as I am concerned. My suggestion, if 300 rwkw is your max target, then I would go forged pistons and RB26 rods with ARP rod bolts. If you want to go over 300 rwkw, then I would go with forged rods as well. If you are happy with 250-270 rwkw then the std pistons may well be OK but you need to very confident in the tuning, keep up the maintenance and test often. My 20 cents worth, with change :wavey:

#4, you mean it's stock standard? No mods at all, not even exhaust?

Me bad man, nope I just call 'em like I see 'em. The old 20rwkw and standard turbo question, I don't have a real answer to that one. If you are at 1 bar and 200 and a bit rwkw then the turbo won't last to make the extra 20 rwkw anyway. Most likely the cams will lower the boost level by reducing the resistance. But at the same time give higher airflow for more power. I really don't know, haven't tried it, but it's logical. Personally, I would upgrade the turbo before I did cams, but you already know that. :wavey:

It's not. Preload is irrelevant, a 100 lbs per inch spring always takes 100 lbs to move it 1 inch. Ride height is usually centre of wheel to guard, vertically. I prefer R33 GTR's no lower than 350/355 mm front and rear The sill to ground measurement should be close to parallel, never nose down Std spring rate (from memory) is 175/125 lbs front /rear. That's 3 kg/mm and 2 kg/mm 12 kg/mm is 670 lbs per inch, even on the race GTR's I have never used a spring rate that high for R tyres (slicks are a different matter). On the race GTR's we would usually run 400 to 450 lbs front and 200 to 250 lbs rear. That's 7/8 and 2.5/3.5 kg/mm. Hope that helps :wavey:

Depends on the brand of cam pulley. Easy to check, each tooth on the cam pulley is 15 degrees crankshaft. Just count the notches for one tooth. :wavey:

Ok I'll have a go. It sounds like carbon deposits from cooked oil, maybe from the turbo bearings. They run down from the turbo and sit in the sump, some get picked up by the oil pump, but the oil filter catches them before they go any further. Some questions; 1. Has this been happening for more than one oil change? 2. How many K's between oil changes? 3. What oil filter are you using? 4. What mods have you done (particularly turbo)? 5. Car usage pattern, traffic, circuit, drag etc? 6. Do you cool the turbo (and the rest of the car) down before you stop? 7. Does it make any strange noises? 8. Running temperature? A bit more searching I am sure will we find the reason and an answer. :wavey:

We have the Tomei 260 degree Poncams in the R34 GTT, it makes more power EVERYWHERE than standard. I can highly recommend them, worth about 20 rwkw max power and give a ~25 rwkw average power increase. Tip, we found adj exhaust cam pulley is not required, their std timing was spot on. Hope that helps :wavey:

Oil cooler = good idea Sump = not necessary for a road car Transmission = very, very strong, we run 650 bhp all the time through std transmissions and never have a problem Driver abuse = most common problem, no matter how strong, you can break anything if you try hard enough Poor servicing = second most common problem, if you don't service it, it will fail Tuning = third most common problem on light tune GTR's and most common problem on hard tune GTRS. Make sure it is tuned properly and leave some margin. Hope that helps :wavey:

My suggestions follow, not in any particular order; *Z32 AFM not required until turbo upgraded. *R32/33 GTR injectors are top feed low impedance and R33 GTST injectors are side feed high impedance. So I would check that carefully when you have the car. *Dyno check is a good idea but not much to "tune" with std ECU Hope that helps :wavey:

Ours is a DAYZ as well.

Hi rev, I started this thread (unusual huh?) because I was getting tired of people saying "dynos are crap" and "the only way to tell how much power your car has is the 1/4". Now we all know that the dyno is only as good as its calibration and its operator. But the 1/4 has many, many more complications that make its results inaccurate and inconsistent. So this thread is here to flush out the thoughts of people, challenge their thinking and kill off a few myths. And you know how much I like bumping of myths. Best of all it gives a central repository to all those who want to know about such things, a quick link saves a lot of typing. So hop on for the ride or jump off, it matters not

Unfortunately I have had crap results, that R34 GTT is just an example of the sort of discrepancies I have experienced. Maybe because I do lots of things to make a car faster, not just the engine. If you just work on the engine all the time and you gradually increase the power, you MIGHT get consistent results. But that's not what I do, I train the driver, I tune the suspension, I move the power around (not necessarily change the max power), I change the gearboxes, I take some weight out, I change the 4wd settings etc etc. I can make a car ~1 second faster over the 1/4 with the same power. The drag power calculators simply can not handle that, they keep coming back with the more power answer. So I simply can't trust them. :cooldance