DC350

Which one would be better? I'm thinkin the newer ones. But i could be wrong? whats up guys


Evan

scathcart

S5 is better. They have lighter rotors so they redline at 8000 instead of 7000, and they have higher a compression ratio for more power.
A few other things, but this the most basic differences. (apex seals for one, and type of recess on the rotors themselves, etc.)
Sean

go_speed_go

The series 5 out of the box will produce more power, but it's also a little more fragile.

Series 4 motors seem to go longer before going POP.

Suparslinc

The Mark V had a ECU that was 6 times faster, revised intake (heard up to 10 hp gain on Mark IV just from swapping the VDI from Mk V) and I disagree about them being more fragile there is no proof an electronic OMP is less reliable than mechanical that I have ever heard of, if thats what you are referring to.

go_speed_go

My point was that so far 86-88 motors have put on more milage before wearing out or blowing up.
In my experience and from talking to a rotary engine builder of 15 years, the Series 4 will last 20-30k miles more than a Series 5.

There are plenty of variables that can skew individual cases, but on the whole, the 4 is a more durable motor.

pearlwing

Suparslinc, you just said that by putting a series V intake mani on a series 4 you can get up to 10 hp by simply bolting it on?

Icemark

On both points... the ECU is 16 bit on the Series 5, and the series 4 is only 8 bit, but they both have the same processor clock speed, so it is not anymore faster, it can simply process more infomation at a cycle. The biggest advantage to that is in emissons.

The electric OMP is more prone to failure on the series 5 and 6 cars than the mechanical set up in the series 3 and 4 13B. A common racer thing is to subsitute the front cover of the series 4 motor onto a series 5 motor so the mechanical OMP can be used. Now you loose a HP or two and it weighs slightly more using the mechanical OMP but its reliabilty way out-weighs the loss.

As too long term reliabilty I too agree that the series 4 motor is slightly more reliable, however I wonder if they had put a 7000 RPM redline on the series 5 motor if it would last just as long. I suspect it would.

pp13bnos

iTrader: (1)

The most common thing "racers" do is just get rid of the omp all together, and run pre-mix. CJ

Suparslinc

Well I never said I was an expert, but someone claimed they could back up that a VDI adds something like 10 hp to a series IV, dyno tested or something which might be a load of crap, I can't back that up myself no experience.

Thank you for the info on the processor IceMark thats cool. I just read that is was 6 times faster on some page not any more details. Yeah sometimes I miss my series IV...

von

from all the series 5 compared to 4 mileage. I would have to say that thier even. More people have 4 series than 5 so u get more opinions for the 4. In my opinion assuming u let both engines die naturally I think 5 would last slightly longer.

HuggyBear

well i would certainly think a series 4 would last alittle longer..... its running on fewer horsepower.....