New to Thunder Roadsters and the FJ1200 engine

[driftopia]

First of all, it's awesome to see such an active community. Gives me a bit of nostalgia.

My name is Chris, and I have been lurking for a bit. I do a bunch of racing and purchased a Thunder Roadster earlier this year. The car has the Yamaha engine and is an absolute blast to drive. (Still not sure if it is the 1200 or 1250) I am here to learn everything I can about optimizing these engines. I have a bunch of questions and will make a post later for some help.

But for now, I just wanted to drop by and say hello.
 
Here is an image of my first outing in the car. That is 9k rpm in 5th gear at the entry to turn 1. The engine is incredible in this chassis.
   

And some footage of a fast lap at Barber Motorsports Park before the engine heat soaks in the summer heat.

[Pat Conlon]

Welcome Chris, I was not aware that our FJ/XJ engines were still Competitive in the Thunder Roadsters.
I recall the Hayabusa engines were the popular replacements.

Cheers
Pat

[driftopia]

That is correct, but there are still a lot of unconverted Thunder Roadsters out there. The Hayabusa ones are significantly faster, so our sanctioning body allows the Yamaha-powered ones to run in a power-to-weight class called Super Touring. I also hate to pull out a perfectly good motor, so I am going to optimize this one as is. The only thing it is lacking is a little more power to consistently run at the front against the BMWs and Fords in the class.

But I did pick up a spare chassis without an engine for super cheap to do the Hayabusa conversion for next season.

[RPM - Robert]

All the Thunder Roadsters came with 1250s in them. Someone could have swapped a 1200 at some point but it would not have been legal to run in INEX events. A quick way to determine if 1250 or 1200 is the serial number on the case above the clutch cover. It it is flat it is a 1250, if it is a raised triangular shape it is a 1200.

[driftopia]

Thanks a bunch. That clears up a lot.

[RPM - Robert]

Big cams, big valves, and a bit of headwork should net you more than 20hp.

A limited slip would help quite a bit we have built a bunch for people over the years.

Putting a 17" aluminum wheel and going to a hoosier A7 or R7 would net you a few seconds a lap as well.  XXR makes a 17" with the correct bolt pattern so you can put a better tire on it and keep the same overall height of your current tire. If you do go to a radial tire you will need to stiffen the suspension up quite a bit.

What are your corner weights sitting at as well as cross weight?