Hymee

iTrader: (1)

Some would argue that is 10 points

rotarygod

The '87-'88 Turbo II compression was 8.5:1. The '89 and on turbo rotaries were all 9.0:1. Even the '84-'85 Turbo 12A 1st gens in Japan were 8.5:1.

Richard Paul

iTrader: (5)

Hymee, If you tried e mailing me I still don't get any, havn't for 10 days. out works in, negative. Use PM or??

Richard

IKnowNot'ing

Thanks,

I found some data in SAE paper 900036 ('90 MY 13B T/C with single turbo).

- The previous NA version of the 13B was 9.7:1 CR ('84 MY)
- The single turbo version is 9.0:1 CR ('90 MY, was 8.5 on '86 MY)
- Boost pressure is as follows (approx) :
> 60 kPa at 2500 rpm
> 50 kPa between 3000 and 5000 rpm
> then going down : 30 kPa at 7000 rpm

The paper also says that detonation was a real issue and that an improved knock control had to be fitted on this engine.

The figures about in line with low pressure turbo versions of Saab, Volvo... although these vehicles are a decade newer and might have benefited from more advanced electronics.

I don't think the rotary can sustain higher boost than its piston engine counterparts. Nevertheless, it would be nice to get the same info about the last generation of twin turbo RX7.

PS : I found 4 SAE papers on older rotaries accessible to all, on a website. Should I put the URL on this forum?

Drewstein

Really?? Then how did 5 hours in my garage at home on a Saturday net me 70 more rwhp with nothing else than swapping from a roots blower to a twin-screw (380rwhp --> 450rwhp)?? Same boost and the twin-screw was dynoed in 105+ degree weather when the roots was dynoed in 80ish degree weather so there may be more of a difference. You do not need lower compression numbers if you stick to moderate boost. 6psi will raise 10.0 to roughly 14.0 at peak boost. In the renesis this will be perfectly acceptible since only the apex seals are at risk. Boost won't pop those, instead detonation will. That is because detonation will exponentially increase the pressure the seals have to take.


Remember- at 14.5psi and 695 cfm, the Eaton 112 consumes 84HP at 13000rpm. The Kenne Bell Twin
Screw uses only 58HP (30% and 26HP less)

IKnowNot'ing

Here is what you said and we're arguing about : just bolt a twin screw in lieu of a roots on an aftermarket kit.

Here is what you actually did : bought a full twin screw based KIT for a OEM supercharged engine.
This KIT includes (copied from Kenne Bell's website) :
• Kenne Bell OPTIMODULE to reprogram fuel, spark and trans**
• Kenne Bell Quick Shift Valve to improve shift firmness.
• BOOST-A-PUMP included.
• All Parts inlcuded in kit.
• Best engineered kit.
and as I can see on the pictures, it also include some adaptor pipes on the intake and the exhaust.

Do you think it'd take just 5 hours to design this kit? I don't think so... And it's certainly not what I'd call just slapping a twin screw on in the roots blowers place'.

You lied, you still deserve the comment!

Drewstein

I just bought the twin-screw used without all that extra crap from a guy in califorina, so don't accuse me of buying that crap. My valve body was ordered from an entirely different vendor months before I got the blower. My tune was done on a dyno weeks after I personally installed the blower. The BOOST-A-PUMP is snake oil and I would never use it, instead going with twin 255lph fuel pumps (got money you don't know what stock is and don't look it up). There are no aditional pipes for the intake or exhaust. Exhaust being impossible because a twin-screw has nothing to do with the exhaust (but you knew that right?).
I'll post pictures when I get home in 3 hours of me litterely pulling off the old blower and using all the OEM gaskets/bolts/hardware to put a knew one in its place. 5 hours to swap. In the 8's case, the roots manifold may need to be slightly modified in order to accept a different bolt pattern (which any decent metal worker can do). The way the pullies are driven are the same and where they sit are the same. If one fits, the other will be able to very easily as I said before. But since you think a roots blower would effect exhaust I don't know why I'm having this convo....

I have no reason to lie to you guys since I want to see these things run some decent times with decent dynos. My knowlege is based in blowers and nitrous and I will suggest what I think is best for the application because I don't want a blown motor as much as the next guy.

IKnowNot'ing

By intake / exhaust of the SUPERCHARGER, I mean inlet / outlet.

It seems I've been a bit hard on you : so the Kenne Bell S/C has exactly the same bolt patterns, flanges and dims than the Roots??

Drewstein

Close enough as far as bolt patterns. The roots style blowers sit on a custom intake manifold which can be easily swapped between roots and twin-screw blowers. Even if the manifold was the adapting problem, the rest of the kit would be perfectly interchangeable with is key. An adapter can be made by anyone with metal working skills. It's the pulley, belt, intake design you could transpose between kits with no modification. Both blowers draw in air the same and spitit out the same, it's the innards that are different.

Pics...

What I got-


Before-


During-


After-


People have had to re-drill some mounting holes on blowers in order for them to mount up properly. Not that bad of a swap.

IKnowNot'ing

Drewstein,

Quite transparent! I'm sure you're dealer wouldn't notice a thing if they had the car for a service!

Omicron

I don't think ANY form of forced induction is going to be considered a "stealthy" install, IKN.

IKnowNot'ing

I was not being sarcastic. On this Lightning, I think the S/C swap is very discreet.

Drewstein

Well I don't trust anyone with my vehicle, including the dealer. I do all my own service and work in order to avoid stupid lot attendents or mechanics from touching my baby. I learned how to service my buddies RX-8 so he can mod with pleasure and not worry about stealership problems. People at car shows think it's the stock roots blower that was polished and several mechanics asked me if it was supercharged.

On the 8, we want to modify the stock plastic to conceal the twin-screw so people will have no clue. Picture the intake filter up front running straight back up to the throttle body and intake plenum, that keeps running straight back to the blower inlet where it curves down and connects. It would sit completely over the blower almost hiding it, but if we trim the plastic properly, maybe we can mount it up to the sides of the blower and over the motor. Top secret blower unless you know what to look for. Just waiting for the kits to come out and we're sold! :D