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Needs more boost!
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Discussion Starter #1
And by "big" I mean perhaps doubling the stock ~76bhp figure.

I'm not a n00b to engines by any means, but I have never had a GPZ600R apart. Based on my limited research and some reading in the manual, it looks like pitted rockers are a something to look out for. The silent chain primary drive is also something that makes me go "hmmm."

Despite that, I like the vintage appeal and the sound of these engines and want to explore adapting EFI and forced induction to one. Has anyone here tried this sort of thing on this specific engine or know of any good reading on the topic?
 

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Doubt this is the place to ask your questions as most of the bikes here are air cooled and carbureted vintage models. Not a lot of know-how on doing the things you are looking for, I am afraid. If wrong, and someone jumps up to answer, my mistake...
 

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Needs more boost!
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Discussion Starter #3
Yeah, it was a calculated risk since most of the good GPZR information I have found is in this forum.
 

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Is this type of modification cost effective/practical? Never, especially when you can buy the extra horsepower with just an increase in displacement, without all of the headaches.
 

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Needs more boost!
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Discussion Starter #6
Is this type of modification cost effective/practical? Never, especially when you can buy the extra horsepower with just an increase in displacement, without all of the headaches.
With that kind of answer, it's obvious I'm looking in the wrong forum...
 

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itching to ride
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These engines are already almost at maximum output. Using forced induction would be the only way imo and I doubt the bottom end could hold up to the boost. I would agree with sfair, it would be easier to just get a different bike if your goal is to get around 150 hp.

If you choose to go that route however I would love to see your work and I am sure others here would as well. If you decide on a different forum then be kind and post the link in this thread so we can go have a look.
 

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Needs more boost!
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Discussion Starter #8
With that kind of answer, it's obvious I'm looking in the wrong forum...
Sfair, I didn't mean to sound insulting, BTW. It's just so frequent that someone not taking the easy way is met with defeatism, particularly relative to motorcycles with the stock answer being "get a bigger bike." I ride the road less traveled. There's less traffic. :razz:

You should see one of my four-legged projects. It makes turbocharging an old GPZ look like a fairly modest endeavour.

These engines are already almost at maximum output. Using forced induction would be the only way imo and I doubt the bottom end could hold up to the boost. I would agree with sfair, it would be easier to just get a different bike if your goal is to get around 150 hp.

If you choose to go that route however I would love to see your work and I am sure others here would as well. If you decide on a different forum then be kind and post the link in this thread so we can go have a look.
There isn't really a goal per se except for maybe avoidance of immediate failure. ;-)

I thought forced induction was the obvious choice too as among my collection is a Garrett GT15 that would be sized well for 120-150bhp and ~14-15psi of boost. The engine is already rated at 76bhp, so 15psi with intercooling should about double it and 8psi ought to make a comfortable 120hp. In reality I have enough hardware to do far more sinister things to an engine. :twisted:
 

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itching to ride
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2,215 Posts
Yeah 15 pounds will about double your hp as atmospheric pressure is 14.7 at sea level. of course running that much boost I would think the compression would of necessity have to be lowered which would also drop the starting hp prior to boost.
 

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Needs more boost!
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Discussion Starter #10
Stock compression ratio is 11.0:1, right? I think it would tolerate 15psi with intercooling and good pump gas if not a splash of 100 for safety. It would make the effective compression ratio about 22:1. 20:1 is pushing it for car engines, but the high RPM and smaller chambers of the GPZ will make it less prone to pinging. Water injection is another option.
 

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1. How would you modify the existing ignition curve required for a turbo?
2. How would you deal with the extra heat?
3. What mods would you do to the clutch?
 

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Needs more boost!
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Discussion Starter #12
1. How would you modify the existing ignition curve required for a turbo?
2. How would you deal with the extra heat?
3. What mods would you do to the clutch?
1.) Standalone EFI with 3D spark control.
2.) That's part of the reason for this thread. Besides the obvious larger radiator, I don't know what other cooling system improvements can be made. Water pump housing? Impeller?
3.) If needed, stronger springs, a billet pressure plate, and if absolutely necessary, a billet basket could be done.
 
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