Race-Gas 600 IQR VS. Non-Race-Gas 600 IQR.... Comparisions??

[mountainhorse]

A sincere question that I hope those answering can put some effort into.

Looking for "hands on" experienced answers.

An IQR 600...pick a year.... what HP does a properly tuned one make on Race-Gas (with race-gas head & pipe)?
What does that same engine/sled make, HP-wise, on lower-compression head & pipe w/91 octane... properly tuned of course? (Say that a seasoned/vet factory level mechanic is tuning these).

Then.... MORE importantly.... What is the 'character' of these two scenarios (hi-comp/race, lower-comp/pump-91) on the same sled... HOW do they run differently? (eg throttle response, rpm recovery, acceleration etc)... the PRO and CON for each side would be nice as well.










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[AKrider]

I had Carl's Cycle Sales machine a low compression head for mine so I could run 87 octane gas. I got sick and tired of mixing either race gas or avgas with pump gas to be above 92 octane that many people recommended. While I don't mind premix at all, mixing different types gasoline was a huge hassle. Like a dang science experiment each and every time. Plus having to store a drum of avgas or race gas and siphoning it out got old really quick.

After the installation of the low comp head the sled lost a little bit of its snap and felt smoother but it was no big deal and not a night and day difference. It still has quite a bit more power and snap than the cfi 600 as I also own one of those in an RMK. I'd do it again as it makes an excellent sled easier to live with.

 

[MrIQR]

Many variables to that question. Are we talking as delivered or what is ran in pro mod class on race fuel?

I believe the in 14' they dyno'd at 143hp as delivered from the race department at about sea level, it was actually posted here, I think it might have been crank shop who did it? It's considerably stronger then a production 600(125hp)

full race spec mod would be considerably stronger.

The throttle response and snap of a race fuel motor compared to a low comp is like comparing a production 600 to 800, it is huge. You aint clearing any triples out of a corner on pump gas.

 

[dodger]

realistically you have to be in the area 20HP difference between an IQR 600 race motor and a IQrr with the 600 HO motor. The RR with the HO was so far off from the factory that it takes some finnagling to get tuned properly. When done it is fun, but no speed demon.