Omicron

It sure looks like the most boost we're going to be able to add to the stock Renesis is less than 8 Lbs. While this will be ok for a while, and we should get WHp numbers approaching 300, what I would like to know is what all will need to be replaced if we yank the engine and build it stronger to take more boost? I know the rotors will have to be remachined to lower the pre-boost compression ratio, but what else? Bearings, possibly remachine side seals, etc?

mysql101

When you say 300, is that 110 more hp over the 190ish that people are dynoing, or is that over the 238 that we're supposed to have?

davefzr

Hey.. what what about the sunflower thread Got any updates?

When you say, "it's almost here", it really leads me to believe that you know more than are telling us... Rrrrrr

davefzr

I think it's over 190... as 350 flywheel hp is what one.. is producing...

rotarygod

I think that since there is still so much crying over how much power the car actually makes, that it would just be safer to say that the car will make so much percentage more power than stock. That is all that matters anyways. Actual numbers mean nothing. Performance does and it isn't directly tied to any certain number. Which sounds more impressive, "My turbo makes 300 hp!" or "My turbo gives me 50% more power over stock at only 8 psi!"?

rotarygod

I don't think we are physically limited to 300 hp. Stock (remanufactured!!!) 13B-REW engines in the 3rd gen RX-7 have been boosted up to 600+ rwhp and lived. The Renesis should handle more than 300 hp. That isn't much more stress. A 50% increase in power does not translate into a 50% stress increase in the engine. It is far less than that.

What is limiting us is the stock ecu and fuel system. In my eyes a "stage 1" boost upgrade is good up to about 250 rwhp or so on the stock fuel system. A "stage 2" would include a completely upgraded fuel system that would include necessary fuel tank modifications, fuel pump, return fuel line, fuel pressure regulator, larger injectors, etc... Of course then you have to fool the ecu into not realizing you modified the stock fuel system since it now works differently. This shouldn't be that hard. This should be able to take us from about 250 rwhp to near 350 rwhp or so. After this point we should probably upgrade the ecu to a Motec unit and then start building circuits to piggyback the factory ecu into thinking that the car is still running perfectly so it doesn't give us error codes at inspection time.

All of these numbers are more guesses than anything so don't be mad if I'm off. It is really just meant as examples of what needs to be done and in what order.

Once we get a new complete standalone system, the next limitation will be the engine. I don't see any reason why the engine needs to be torn apart and strengthened when there are so many other things to deal with first. If you can afford to get this far, you should probably just buy a new Renesis and start as a ground up build. That way you can just swap engines out rather than have the car down for any long extended period of time.

Broke_Apex_Seal

Why do people get stuck on how much PSI can I run? PSI is a good way to measure but it does not really tell you what power you will make and a general comment of it can only handle 8 PSI is kinda off. Back up your facts with why 8 psi is the max. If the fuel is there the boost can keep going up.

RXE16T

Problem is that the fuel supply will be the biggest hurdle to any higher boost levels and hp.

The stock fuel pump and fuel tank are an inadequate design for high hp.

The problem lies in its design and its up to the ability of the aftermarket to design something which will not require relocating the tank and pump to the trunk of the car.

Broke_Apex_Seal

crush the FPR and some race gas the motor will take more than 8 psi. I can assure you of that. BTW I have dont think the fuel tank is going to be an issue. IMO of course

StretchSJE

Could you elaborate on that?

50% more power = combustion >50% more air, >50% more fuel, and in >50% increase in many internal forces. I suppose the question is- which of those forces translate to wear? RPM's stay constant and thus I imagine most mechanical links aren't stressed much more with the added pressure, but the seals are required to withstand >50% more pressure, are they not? What about new generation of heat?

Zaku-8

I don't know exactly how it works in rotary engines but in pistons many of the added combustion forces or pressures in a turbocharged engine occur well after crank angle has passed the point of highest compression=>force=>stress, due to the time it takes for a full burn. So peak loads arent increased as much as power, which is an average of pressure over the entire stroke. I forget if and how, but inertial tensile loads of just the piston or rotor moving might cancel some of the compressive combustion forces too. This is in Corky Bell's book on TC which is worth a read.

Omicron

Ok, good so far...

What about the side-seal issue, and/or porting?

Omicron

Who said I stated this as a "fact?"

Zaku-8

8psi isn't an absolute limit, of course not... but after that it becomes a fairly involved kit, and isn't really a "bolt-on" due to the complexity.

This is the list as I see it that needs to be done, based on what I recall people saying on this board. it may not be accurate and the terminology is probably off

1. fuel system. more pump capacity, more injectors. Paul Yaw had to remove the fuel system and fabricate his own return lines

2. ECU. I think most of the obstacles in the development of current kits centers on this. IMO Racing Beat's approach to ECU tuning seems the best, considering that their entire focus is to understand what is apparently the most complex human device ever made, whereas other ECU mods focus on piggyback methods for basic parameters. Hopefully RB's solution will integrate well with a turbo kit.

3. I guess MAF issues will probably be addressed with this upcoming generation of kits but maybe not.

4. side seals. First reports I think in March, surfaced again in August. I think people agreed it was not an issue for NA stock but under FI and even ported pressures significant wear and clearances will be seen. fix is by smoothing out that port edge, something that probably won't be done with sub 8psi bolt on kits.

5. expanding plastic manifold needs to be replaced? I don't think anyone on the board knows what's going on here, based on the reports.

6. engine's compression ratio is 10:1. Rotarygod pointed out in another thread that crispeed is running a 9.7:1 FD for 600+whp, which is way more power than a stage 2 calls for. So compression may not have to be reduced yet. There are many good points in the boost solutions thread as to why the compression ratio may not have to be changed

6.a. Another reason not to change the rotors may be because they are very light... I'm not sure what bearing that has on FI, I ask anyone to explain if they know.

7. Transmission needs to be swapped, probably.
auto trans people might want to look into sending their units to someplace like Level Ten to get tranny and converters bolstered to handle FI power.

Can manual transmissions be upgraded for higher torque? If not, what options are there other than the FD or RENESIS 4-port ROW 5-speed? how much do race transmissions cost?

Omicron

There ya go... that's more what I was after... :D

rotarygod

He is building a race car and their class does not limit them to the stock ecu. What would you do? Of course you'd replace it. He is using a Motec system. Their system can control the drive by wire. They do not need to worry about emissions either. He replaced the ecu because he'd be a fool not to. You can't tune the stock one.