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Post by mattturbocar on May 26, 2013 8:10:47 GMT
Hey there,
I know this question has been covered on the old forum, but I can't remember the answer.
My current engine has suffered headgasket failure and is an extremely heavy breather, so I've got to swap it out.
As it is summer time I want to get an engine in ASAP and I have a stock GSXR1100wp (CR 10.5, cast pistons).
I have a good intercooler so air temps only go up ~5degC at 12psi and good control of AFR (Megasquirt + LC1).
Presently I am running 12psi of boost, but I guess I will need to drop that down.
How many PSI is sensible to keep this engine functioning for a year or so (that is maybe 1000 miles and a couple of track-days), while I rebuild the sick one? I don't mind buying the expensive (98RON) petrol if that is a consideration.
Thanks,
Matt
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Post by katana on May 26, 2013 11:04:51 GMT
With decent fuel and control of inlet temps and AFR, I don't see 12psi boost being a problem if you also
have good boost control! If its internally gated or single port external gate then I'd be worried about boost
spikes causing det and broken engine!
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Post by mattturbocar on May 26, 2013 22:40:03 GMT
Really? That sounds like a lot?
Have you done this yourself?
10.5 CR and 12psi, I wasn't planning on dropping the CR as I'd prefer not to start opening up this engine.
Matt
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Post by katana on May 27, 2013 16:50:44 GMT
No but if it was a single or multi carbs I wouldn't have advised it - you have better control over fueling and ignition.
Less advance can help offset the compression but that causes hotter exhaust which will spool the turbo better. Again
the watercooled motor will help to reduce hot spots. Anyway how many miles / minutes are you planning on WOT and
max boost? If the tune up has killed the previous engine then ignore anything i've said, and then lose about 6psi boost
- that'll be safer!
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Post by mattturbocar on May 27, 2013 22:58:48 GMT
Thanks for the detail.
I'm running a td04-16 turbo which uses an internal wastegate. But I don't get boost spikes. I have a fair amount of inlet volume (more than on a bike) so that might have tamed this slightly. Also my rate of acceleration will be slower than you guys because although I've got more tyre area, I also have much more mass to accelerate (car weight of 470kg).
Not sure how many miles/minutes at WOT, but maybe 50% of the time on the track with a track session lasting 20mins. Just guesses here.
The last engine died from overheating, which was a failed head gasket dumping all the water out. It was already a heavy breather and I did abuse it rather (duff fuel pressure gauge meant I was giving it low pressure and so I probably ran a bit lean underboost too). All pretty inexcusable but once I realised it was breathing heavy with no spare liner volume to rebore I stopped loving it so wasn't sufficiently observant of the gauges.
Old engine coming out at the end of this week.
Matt
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Post by katana on May 28, 2013 9:04:57 GMT
I would imagine the heavy breathing / oil past the rings is a likely cause for detonation that took the head gasket out.......so let that be a lesson learnt! LOL.
Also don't forget that (within reason) the more load on the engine, the harder the turbo will work. Does the intake feature an intercooler? 10 minutes of
WOT / max boost with cast pistons is probably going to kill them! Unlikely to melt the pistons - I found the rings to be the weakest link as they are usually too
near the piston crowns for turbo use so tend to overheat and lose tension then allow blow-by and you are back to heavy breathing again!
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Post by mattturbocar on May 28, 2013 12:55:29 GMT
Yup I have a decent front mounted intercooler, it works well. I will probably turn things down a bit while I get some miles under my belt. Then turn it up and break things again!
Strangely enough I wasn't burning much oil, but it was breathing heavy, but I agree that sick engine + boost = very sick engine.
I will build it all up and see what I get. Thanks for your thoughts on this.
Matt
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Post by nomex on May 28, 2013 13:15:55 GMT
How much the intake temperature is? Heavy breathing = time to change pistons. What ignition you are using?
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Post by mattturbocar on May 28, 2013 14:48:33 GMT
The crankcase breather blows out a lot of gas, anyway I have given up on that engine too many issues (lightened crank is a pain).
The pistons and bores were an e-bay special, and sadly didn't live up to their marketing (pre-worn!).
Ignition is by Ford driven as wasted spark from megasquirt (MS2) BIP transistors.
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Post by pasis on May 28, 2013 16:21:39 GMT
Hi Matt.
As far as I can remember, compression ratio with standard pistons around 11-11.5.
I think it's too much for the turbo.
I made my WP motor, 1192. But I have the same problem. I'll be to disassemble the engine and find out what the problem is. I have a lot of oil off the ventilation system motor.
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Post by nitro on May 28, 2013 16:54:07 GMT
I´m surprised that it just melt teh headgasket.
FYI: A few years ago I had 0,9bar (13psi?) on my 1074cc / 2mm spacerplate - 8,7 : 1 CR on the highway with 102 octane, intercooler etc... and was still affraid of melting my pistons. But they kept 8)
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Post by mattturbocar on May 28, 2013 17:05:02 GMT
Pasis,
Great to hear that you have found this site too.
You are correct, I was wrong 11.2 seems to be the compression ratio. Not sure where I got my 10.5 number from, but it looks like I got it wrong.
FYI: my broken engine is also at 1195cc (or thereabouts). No surprise that the clever people out there have already realised that going with these bigger capacities is a bad idea in the gsxr1100wp.
I guess I need to install a base spacer to keep things sensible.
1mm would bring it down to 9.4, 1.5mm down to 8.75, what do you think?
Matt
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Post by pasis on May 28, 2013 17:07:14 GMT
Hi!
I have a 1192 motor, CR about 13. fuel 98 and VP C12
I assembled the engine in October, and immediately took on a motorcycle drag race.
There was no time for running the motor. In May, I again went to the races.
At the end of the race I had problems with overheating, and by all accounts I punched gasket.
Perhaps the point is not a very good head. I have not polished.
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Post by mattturbocar on May 28, 2013 17:09:22 GMT
Good to hear that you are treating you engines with love  what is VP C12 |
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Post by pasis on May 28, 2013 17:13:29 GMT
I'll be disassembling the engine and find out what was the reason.
My friend's 1146 engine, and the same problems were in the past year.
Now I'm doing a motor for a client 1117RF. Let's see how he will behave.
On it we ordered the turbo pistons MTC and thick spacer (falicon) under the block.
If I have another problem with this block, it will seek to block the bandit 1250, and to mount a it. I have already ordered for the cylinder gasket bandit to compare them.
Or you need to look for a big block WC.
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