Xontroi

My dear friends i was thinking about install a Novarossi N21-7T in my Gt car.
My first question is that do you believe i will have problems with temperatures due to the smaller cooling head?
I know that there is also the N21 rally model of this engine with a proper head but the on road has 1500 RPM more than the rally model.
I hope any of you had already experience of something like that.

P.S. Do you believe that 7 port is too much for rally game. It would be better to go for a 5 port?

desotoracing

Go with the N21R7. It has plenty of power and the bigger head. 7 port engines are fine for GT cars if they are set up correctly.

Xontroi

Thanks for the answer buddy. What if i can find the on road engine almost at half price? Do you believe it worth the effort? Will i have problem with over heating?.
At the pictures you can see the fitting of my current engine (LRP 28) with Bysm lexan

Roelof

You can always ask for an used offroad head. Engines comes and goes so there must be used parts available.

blis

I would seriously consider the fuel you will be running as well. Perhaps Roelof will add some input but I would take a guess and recommend you run a lower oil content and run it rich to aid with cooling. If you run a high oil content and rich you will very likely damage your bearings quickly trying to compress a wet oily mix. Perhaps even 16% nitro too...

With your wheels spinning in rally and not much ventilation she will get hot.

Also the tuning will make all the difference, perhaps running a richer bottom end and run a smaller venturi to restrict the amount of air at lower rpms, which all then has to beg to question, why run a hi-performance Hi-RPM On Road engine?

I'd still go with a NovaRossi, the metalurgy, build and quality will give you reliability, it will be a better and longer lasting investment, providing the application of the engine is setup to the conditions you want to run in.


These are just considerations I would have, dont take any of it as gospel. I'd want more experienced engine ppl to give you the heads up than me.

Xontroi

So dear Blis if i understand right you believe that i will go hot with N21-7T.
I had the hope that two slices of aluminium couldn't give such a big difference
Of course i haven't mind to run the engine richer in order not to get hot.
I want a well performed engine and not intermediate solutions.
I run Byron Race Gen2 25% nitro 11% oil.
I read a lot also at igtforum and some the guys there run some on road engines on GT2.
They didn't mentioned something about temperatures. On the other hand no one told that they were cool.
My last question was what if i replaced the head with another one from rally or from of road engine, as Roelof said.
The 4 holes at the head are the same at some Nova motors. I mean the pattern-distances of the holes.

blis

My point is that a rally car is like a nitro drifter, the engine is revving but there's no air passing across the heat sink. A can am on-road car has it's heat sink totally exposed all the time and it has a lot of air passing.

Im not an engine guru by any means of the imagination but this is simple common sense. And for any air cooled engine that is wheel spinning you will need to use the Methanol in the fuel to cool it down.

But please consider, that a good quality NovaRossi will be a lot more reliable! Regardless it's how you tune it for the conditions and if you wish to look in the Off-Road Engine thread there is a very strong discussion regarding fuels. No one fuel is perfect for all conditions and I believe this is a critieria you should factor into your decision process. Gearing will also play a major part in the strategy, once again completely dependent on the track.

Yes I've strayed from the original post of "which engine" but lets not discount the application of the engine which should have a strong bearing on the decision.

NitroVein

Iīm not sure how the N/R-Basic engines are designed, but if there is a rough anodized surface on the cooling head where it meets the head button you could sand it smooth and flat to help-out with cooling.
Sometimes a little thermal compound for computers can get the job done also, but thatīs sort of a last resort.

Then regarding if "two slices of aluminium" can make that much difference, I bet there is a difference in the diameter also... (and I get it to 1 slice of aluminium... )

Xontroi

Yes you are right. It is only one slice the difference and the rally head is bigger 5mm at diameter but i think it has bigger gaps

Roelof

Onroad engines are well used in GT cars, even with onroad heads. I do not know about the setup but I can imagine that an onroad engine needs a lighter gearing.

MantisWorx

iTrader: (28)

I fought this last week while tuning for my last tanks of break in on my kangaroo. At 265* the engine ran like crap but at 300* it was a beast, sounded and felt like it was right. Thought it was my temp gun but every gun was about the same. So as a last resort I put an off road head on the engine and with no. No changes in tune the engine went from 310* to 220* and fat as a pig! Leaned it out almost a full turn and now it's a demon! So IMO the GT cars need the larger heads to be efficient. The flipside to this could also be the body you run, the locals that run the short alpha bodies and the same engine don't seem to have this issue. I am running the Audi LM body. But I still think you can't go wrong with the bigger head.

Xontroi

Ok So the worst scenario is to go for a replacement of the head.
Could you indicate me what heads could be compatible for this crankcase?
I was thinking something like king headz.
Somebody could write me down the distances at the 4 holes of the head?

latemodel13

iTrader: (101)

I run a p5 head on a 35+21 .

Roelof

I looked on their site and they have replacement heads for RB (like S7) engines. RB is made by Novarossi and is a direct fit.

Xontroi

Can i ask something more in order not to open a new subject?
I was looking at kangaroo and kappo engines of Nova and i can't understand why they cost more than a N21-7T when the specs are lower?