I want to build a N/A motor to go in a circuit racing TVR. I don't want to go the 20B route, and I want to build a high power motor which is reiable, and will only be used on the circuit. I undestand that you can't wring the last bhp out of the thing and expect reliability, so how far can you go, and what do you need to do? I'm sure there is a racer out there, who has spent a significant part of his life, and probably all his money doing this. I just hope he reads this and gives me an answer! Anybody know how much a 2 rotor engine weighs?

 

without the 20b route, think the max you can pull is a little over 200, with a ton of work involved, course you can always drop in a LSx

 

Bridgeport.

 

didn't realize anyone got any sizable amounts over 200 even with heavy porting?

 

bridge port is the only way to go. around 280 hp and a redline at 9k rpms. plus i dont believe bridge ports hurt reliability too much.

 

What is the RPM range you will be operating the car at? Are there any rules in your class banning peripheral ports?

For the most power out of an NA with a powerband starting at 4K (but still making more power then stock below that) peripheral porting is the way to go. Simple, reliable, kinda loud though.

 

Kinda or really-super-duper?

 

Periperal porting is permitted. Will rev the car to whats needed and reliable!

 

go PP

start with S5 internals, get them balanced. RX8 stationary gears, solid corner seals and FD corner seal springs. Stock apex seals, stock springs. Do all the oiling mods, and get an FD oil pressure regulator and a good oil pump.

limit revs to 10,000RPM and it'll run forever, as long as you keep the coolant temp between 180 and 210 and the oil temp as cool as you can make it.

 

Ok ignorance to the fore, what is an S5 motor please?

 

S4 = 1986-1988

S5=1989=1991

 

S5 internals already have hardened stationary gears, so there's no point switching to the RX-8 units. You can just get the existing gears machined for 3 window bearings. Most machine shops can do this for around $50.

The S5 rotating assembly has the highest compression of all NA not counting the Renesis and is also the lightest, so it's the place to start.

You'll want the TII oil pump, a shimmed regulator or the FD part and an oil pan baffle.

Of course, the whole thing will need to be run by a standalone EFI system.

 

That is an impressive sounding car no matter what you do. Rotary TVR = Sweetness. Wasn't it a British guy who helped fine tune the 26B?

 

Thanks everyone, I seem to be getting good information here. So I need to start with an S5 motor.
I'm looking at a motor on the floor, and the seller assures me its an S5, how can I know he's telling the truth?

 

See the FAQ for info on how to tell S4 vs. S5 engines apart.

 

In the interest of reliability I would suggest ceramic apex seals. Will also help for higher revs.

 

they might be a bit pricey, but considering they can save you rotor housings when it goes awol. its a big plus.

 

The NRS ones seem to be quite well received and price is very reasonable(i think there is even a group buy on right now).

In the FD road race car I crew for they lasted all season long, without losing compression (a single turbo application).

 

Yep, PP motor with s5 internals and ceramic apex seals, plus the oil mods listed. You can get 300+ to the wheels with a properly designed PP motor. It will be loud as ****, though, but thats pretty standard for race cars. I believe that exhaust scavanging plays a big role in tuning a PP motor for power, so it will be a good idea to pick the brain of people that have built them before. You might get some other suggestions in the race tech section as well. They specialize in racing specific stuff (obviously).