Rotary Development

[NoDOHC]

Ok, I know this section sees very little use, but I am torn between several paths, so I decided to make a poll.

I have rebuilt or been involved in rebuilding several rotary engines and am not at all afraid to modify them extensively.

I have a pair of lightened, polished, and soon to be balanced, 9.5:1 CR rotors.

I also have S5 planetaries and soon-to-be-balanced rotating assembly. I am debating what to do with it.

I also have a Haltech e6x ECU in a rust-free '86 GXL (no one ever claimed that the paint was good) that is my test bed for new engines. It has turbo drivetrain in decent condition.

The car currently has an '88 four-port engine in it with 10,200 miles on polished 8.2:1 CR rotors. It has a blueprinted stock manifold on it. I believe that my ignition is costing me about 30 WHp (It should make about 250 WHp).

I like doing development. In fact, it was the love of developing new or better products that got me into engineering in the first place.

I have a very long and otherwise boring Wisconsin winter ahead of me and I am looking for a project that keeps me in the heated garage. Because I spent all last winter building small block chevys, I figured that I would devote this winter to rotaries.

Here are the options for the winter:
Leave the engine block alone and strap a GT37 VGT on it - Shoot for 500 WHP @ 14.5psi
Leave the engine block alone and strap a pair of twin turbos on it - Shoot for 450 WHp @ 14.5 psi
Take the engine out, set it aside and build a semi-PP out of an old 6-port block - Shoot for 250 WHp > 30 MPG and 1,000 rpm idle
Take the engine out, set it aside and replace it with a built-streetported 6-port - Shoot for 200 WHp NA
Take the engine out, tear it down and install the balanced, high compression assembly, build a custom intake, install Yukon coils and E8 ECU - Shoot for 300 WHp, streetported NA


EDIT:

I am mostly interested in which of these would be most useful to the community at the moment. I will probably do all of them eventually.

Complicated is not an issue at all. I intend for this to take all winter.

[prrex4ever]

I would go with the GT37, seems to be less complicated.

[NoDOHC]

Since I get to vote in my own poll, I will go with the 300 WHp NA Streetport, as my initial soft-goal was to get 200 WHp (which I have since learned is not that difficult).

My hard goal was 2X NA power @ 14.5 psi boost, this will get me a good view of 600 WHp with the GT37 (which will max it out).

[C. Ludwig]

Originally Posted by NoDOHC

My hard goal was 2X NA power @ 14.5 psi boost, this will get me a good view of 600 WHp with the GT37 (which will max it out).

I'm going out on a limb and saying this will never happen.

[prrex4ever]

Seems like you have a plan, good luck with it.

[Silver86]

i voted for the 4-port option.

[NoDOHC]

I'm going out on a limb and saying this will never happen.

You are right.

First because the GT 37 is out of efficiency at that flow rate.
Second because my 300WHp theories require 9.5:1 rotors, which would never let me run 13.0:1 AFR and 12-15 BTDC timing at 14.5 psi.

I agree that I was a little optimistic when I wrote that thread. (500 WHp is pushing that turbo, actually).

[N.RotaryTech]

I voted for the 4 port.
I wanted to vote for the 6 port, but seeing how its already at 200hp (according to you sig) making it even more powerful seem the way to go.

[Whizbang]

four port here as well

[NoDOHC]

I'll leave this up for a while, but I think I had best avoid anything involving a turbo at this point in my rotary learning curve, I talked to my rotary-building friends (who got me into them) and my 13.0:1 AFR idea was heavily ridiculed. (I still want to try it though). I was also told that 500 WHp with a GT37 is possible but not easy.

Basically, Turbocharging a gasoline engine is a whole new world for me. I have been made to know that if I want to keep my engine intact, I need to stay NA. I originally built this engine to blow up, but now that it has promise of making power, I am thinking that I want to keep it running.

They had also heard rumors of a 275 WHp streetported 4-port NA build using a custom intake manifold, but I still can't find it on the internet.

I appreciate C. Ludwig questioning my overly-optimistic hopes, as that raised a question in my mind which prompted me to run the idea past my friends.

[classicauto]

Originally Posted by NoDOHC

They had also heard rumors of a 275 WHp streetported 4-port NA build using a custom intake manifold, but I still can't find it on the internet.

Wives tale. Most of the full bridge, 10K rpm engines in local race cars around here are only dipping 280ish to the hubs. Some halfie's landing anywhere between 220 and 250.

A custom intake with less porting (and presumabley revs) won't net an extra 40% increase in peak power, assuming 200 to be the practical peak benchmark for a well done streetported 4 port.

If you really wanted to do something experimental, try my next project.

300-350whp max, small turbo (T04-E 57 trim likely.....) with straight water AI.......................................on 87 octane. I don't care what type of block you use, but has to be low grade fuel. That's what I'm planning to do with my recently acquired FB, one day.......one day.

Turbo engines can be reliable. Certainly not as "bullet proof" (ie. as low powered) as an N/A, but don't think you can't just because people have problems....its no reason to stay under the 300whp mark

[Whizbang]

i still want to see some dyno charts

[Whizbang]

im trying to stay away from forced induction for the rally car project simply to do the added complexity (potential failures), added cost (potential inability to fix failures) and the hefty increase in heat (potential failure). short runs would be alright in the heat department, but running miles on end flat out would be hard to pin down, especially for hill climb events.

[NoDOHC]

Originally Posted by GravityFed

i still want to see some dyno charts

Unfortunately, now it will have to wait until spring, as dyno season is nearly over.

The charts that I have so far are posted under intake manifold modifications.

Originally Posted by classicauto

A custom intake with less porting (and presumabley revs) won't net an extra 40% increase in peak power, assuming 200 to be the practical peak benchmark for a well done streetported 4 port.

I think that 200 WHp is selling a well done 4-port drastically short. As I have posted before, I am convinced that mine will make 250 WHp just as it is with a better ignition system that allows it to make full use of the VE curve that is already has. (The explanation is posted in the intake manifold modification thread and need not be repeated here).

Don't forget that I am running 8.2:1 Rotors, a far cry below the 9.7:1 rotors that most race cars run.

Even assuming that I have eeked the last horsepower out of my engine (no improvements to be had with better ignition), I still make 216 WHp using low-compression rotors and a TII manifold (No RE builds here). My intake was piped to the front of the car (cold air intake in the fender), I had stock Racing beat headers and presilencer with dynaflow mufflers and stock y-pipe. I was also running a stock mechanical fan with a bad clutch (stuck in engaged position), Turbo drivetrain and stock tires (more losses on a dyno than low-profile tires on larger wheels). Neither was I running royal purple or some fancy oil to minimize drivetrain loss.

I think that many would argue that I have left a lot on the table there too.

I think that the torque numbers speak for themselves (160 Wlb-ft @ 6100 rpm), The stock port timing will make more torque than the typical streetport as it allows for a more complete intake stroke.

I have long argued that bigger is not always better, I will continue to hold that position. Most streetports are designed for turbo cars, where the late port close allows the car to run more boost. This does not help with a naturally aspirated engine, which needs all the intake charge that it can get.

[NoDOHC]

Originally Posted by classicauto

If you really wanted to do something experimental, try my next project.

300-350whp max, small turbo (T04-E 57 trim likely.....) with straight water AI.......................................on 87 octane. I don't care what type of block you use, but has to be low grade fuel. That's what I'm planning to do with my recently acquired FB, one day.......one day.

Turbo engines can be reliable. Certainly not as "bullet proof" (ie. as low powered) as an N/A, but don't think you can't just because people have problems....its no reason to stay under the 300whp mark

This sounds like a worthy project (not just pump gas but 87 octane - pretty strict).

Unfortunately, my experience lies primarily in the naturally aspirated engine building field. According to my friends, I should stick with NA. For that reason, I think I will avoid turbo projects until I see how high I can go with the NA build.

I wish you the best, for now I will leave the turbo-related development work to those of you who understand the reliability issues caused by turbos and I will work with the naturally aspirated engine, as I understand the potential failure modes on a NA engine.

Please don't misunderstand me as saying that NA engines are bullet-proof (meaning that they are low powered). I mostly am trying to say that I understand the few and logical ways that an NA engine can fail, while many turbocharged engine have given up the ghost for reasons that their owners can't even guess at.

There is no sense of foreboding or danger when I back my NA RX7 onto the dyno rollers. I tuned the engine based on my seat-of-the-pants guesses and ran again to see how that effected the power. I have run AFRs from 12.0:1 to 17.0:1 and ignition timing from 62 BTDC to 26 BTDC and have done my engine no harm.

If I had a turbo, I would be worried about my fuel curve, my fuel pump, my MAP sensor accuracy and my ignition map. I would be watching boost, fuel pressure, water temperature, IAT, AFR, etc. like a hawk during the entire run. With the NA engine, I watched the tach and datalogged.