13100 rpm fourbanger restricted to 9300 redline

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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by ptuomov »

ptuomov wrote: Fri Mar 19, 2021 2:05 pm The starting point is a 600cc four stroke four cylinder engine from GSXR 600 which makes about 106hp @ 13100rpm.
That info was wrong as the starting point. The factory stock unrestricted base engine in the 2015 GSX-R600 bike appears to be making 125 hp @ 13,500 rpm and 50 lbf-ft @ 11,500 rpm. This is the best official info anyway. It’s likely ball park correct because other 600cc four cylinder Japanese bikes made similar power numbers at the time.

In my opinion, a reasonable expectation as a starting point is to shift the same torque peak value down, by a hook or crook, from 11,500 rpm to 9,300 rpm and make 50*9300/5250 = 89 hp. @ 9,300 rpm.
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by ptuomov »

johnef wrote: Wed Mar 24, 2021 6:26 pm Check APE Race parts in the Tech section, they have all the engine specs for each model, of each year.
They unfortunately don’t have tech specs for 2015 GSX-R600 and/or the N738 engine in it. Can’t find much info at all for N738 anywhere.
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by CamKing »

How do they check the cam ?
What specs are they checking it to ?
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by ptuomov »

CamKing wrote: Thu Jul 22, 2021 2:28 pm How do they check the cam ?
What specs are they checking it to ?
That’s a mystery to me. The quality of the technical inspection appears to vary from venue to venue and from country to country. We just got disqualified for wrong size steel wire in the window mesh but the inspector couldn’t tell me much about the engine specs and wasn’t bothered by it. Then there are other extremes where they seem to have stacks of factory technical documents and are tight lipped about it all what they know.

If you were purely hypothetically to cheat by altering the camshafts, how would you do it?
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by BLSTIC »

I'd start by altering the crankshaft gear and tdc indicator so that any degree wheel read correctly to spec but the crankshaft was actually where i wanted it

It's like here in Aus Cleveland engines would oil starve and they weren't allowed to drastically overfill. Tech supposedly had a standard dipstick so you couldn't shorten yours and get away with it. So someone lengthened their dipstick tube and it wasn't noticed because standard checks still worked (secondhand story from many years ago)
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by CamKing »

ptuomov wrote: Thu Jul 22, 2021 2:38 pm
That’s a mystery to me. The quality of the technical inspection appears to vary from venue to venue and from country to country. We just got disqualified for wrong size steel wire in the window mesh but the inspector couldn’t tell me much about the engine specs and wasn’t bothered by it. Then there are other extremes where they seem to have stacks of factory technical documents and are tight lipped about it all what they know.

If you were purely hypothetically to cheat by altering the camshafts, how would you do it?
Hypothetically, let's say the cam spec sheet from the manufacturer says the intake lobe has a lobe lift of 10mm(=/- .025mm), and the duration at 1mm of 240(+/- 2 degrees).
I would design a lobe that's 10mm lift, and 239@1mm, but make it shorter below 1mm, so it has less seat duration.
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by Stan Weiss »

CamKing wrote: Thu Jul 22, 2021 2:28 pm How do they check the cam ?
What specs are they checking it to ?
He really needs to get answers to this.

Here is example from SCCA from years ago.

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scca-formula-ford-exhaust.gif
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by englertracing »

Stan Weiss wrote: Thu Jul 22, 2021 6:33 pm
CamKing wrote: Thu Jul 22, 2021 2:28 pm How do they check the cam ?
What specs are they checking it to ?
He really needs to get answers to this.

Here is example from SCCA from years ago.

Stan

scca-formula-ford-exhaust.gif
Haha
Your not going to get away with much with a checking method like that....

They all ran one engine though.
I seriously doubt that they will do that in a series with a wide variety of engines.
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by ptuomov »

I think every car in all these series has N738 or N377 GSX-R600 engine. So they should know what to check.

It’s my understanding that Suzuki usually specifies the cam duration at 0.3mm. They also specify the intake lash maximum at 0.15mm and exhaust at 0.25mm. I conjecture that this is the end of the ramp in those cams. This all guesses.

If the cams are not on original factory cores I think it’s a fail. If the base circle is reduced, I think it’s a fail. Etc.

In terms of the cams, I think the most practical route might be figuring out from the cam profiles at which point the ramp actually ends and increasing the valve lash beyond the factory specs right to the end of the ramp when engine is warm. This by my logic would reduce the duration that the engine actually sees. The durability would be helped by the 9300rpm redline of the restricted engine instead of the 14500rpm+ redlines of the unrestricted engine (same valve springs etc.)

This is all hypothetical of course.
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by CamKing »

englertracing wrote: Thu Jul 22, 2021 8:15 pm
Stan Weiss wrote: Thu Jul 22, 2021 6:33 pm Here is example from SCCA from years ago.

scca-formula-ford-exhaust.gif
Haha
Your not going to get away with much with a checking method like that....
Yet, I designed a cheater cam for the Formula Ford engines that picked up power. We made a good number of them and never failed tech.
There's things you can do within the machining tolerances, that will pick up power.
We have profiles for the 602 and 604 Crate engines, that pick up about 8hp. You can pull the cams out and cam doctor them, and they look stock.
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by CamKing »

ptuomov wrote: Fri Jul 23, 2021 3:23 am If the cams are not on original factory cores I think it’s a fail. If the base circle is reduced, I think it’s a fail. Etc.
There's usually a machining tolerance on the base circle. Since we would be reducing the seat duration, regrinding the stock cam would only change the base circle by about .002"-.004"
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by ptuomov »

Good to know.
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by ptuomov »

What would we be looking for on the intake side in terms of intake tract length and diameter?

The stock unrestricted engine from the bike has about 11cm in the head and then minimum 9cm to the trumpet opening. There are two sequential throttle plates per cylinder, the downstream controlled by the driver/rider and the upstream one by the ECU. A quick and dirty measurement gives about 38-39 mm diameter for the downstream throttle plates and about 45-46 mm diameter for the upstream throttle plates. The trumpet upstream of the upstream throttle plates starts at 46.4 mm and tapers to larger from there. This setup makes peak torque at 11,500 rpm and holds that torque well enough to give peak power at 13,500 rpm.

What's would be the ideal sizing here when the rpm is restricted to max 9300 rpm, the used power band is 7,000-9,300 rpm, and the 9,300 rpm peak power goes down by -29% relative to the unrestricted 13,500 rpm peak power?
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by ptuomov »

For what it’s worth, the intake port at the flange starts about 36.5mm x 30mm oval. I’m not quite sure I got the second coordinate exactly normal to the flow, but if I did it’s about 900 mm^2 (1.4 square inch) port at the gasket flange.
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Re: 13100 rpm fourbanger restricted to 9300 redline

Post by johnef »

Run CR9EK plugs, give you a little bump in compression, we sometimes deepen the pocket to push the plug down further.
Get a manual cam chain tensioner, its good insurance.
Grind down the cam chain plastic guide a bit between the cams, it creates some drag on the chain. Line bore the cam tunnels, Suzuki is terrible.
No other tricks, you can take a lick off the deck of the block if its passes inspection, 0.025" PTH and it will sing.
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