13b-rew n/a set-up help (racing)
01-23-23, 08:12 PM
#26
almost posted this before, but held back …. honestly if 200 whp is the goal then the broadest power band for a rotary engine is going to be a blueprinted & balanced but otherwise bone stock Renesis. You don’t even need anything more than a simple log-type exhaust manifold on it as the zero-overlap intake/exhaust timing eliminates any potential for exhaust tuning via a tubular header. That’s already been well proven in actual results despite people theoretically arguing otherwise. Limiting it to 200 whp is a rev limiter function, which is going to extend engine life.
Drummond built 270 bhp stock port Renesis in the Mazda Formula Pro race car at the Indy road course, mid-upper 230 whp thanks to the efficient transaxle , runs out of gearing down the front straight
the only significant modification is reworking the rotor apex grooves to use RX7 depth Iannetti ceramic seals. The deeper seal change should be done, but you could use OE Rx7 seals instead if you want to avoid that expense. It wasn’t unusual to get several seasons out of an engine.
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Drummond built 270 bhp stock port Renesis in the Mazda Formula Pro race car at the Indy road course, mid-upper 230 whp thanks to the efficient transaxle , runs out of gearing down the front straight
the only significant modification is reworking the rotor apex grooves to use RX7 depth Iannetti ceramic seals. The deeper seal change should be done, but you could use OE Rx7 seals instead if you want to avoid that expense. It wasn’t unusual to get several seasons out of an engine.
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Last edited by TeamRX8; 01-23-23 at 08:27 PM.
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diabolical1 (04-30-23),
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01-28-23, 05:01 AM
#27
Old [Sch|F]ool
Headers work great on zero overlap piston engines... exhaust flow has inertia that can pull the combustion chamber down below what the piston could normally "push" out, even down to a vacuum(*), which reduces exhaust residuals as well as helping things get moving when the intake valve opens.
Maybe rotaries are different because the exhaust pulses happen so close together? Does the shared exhaust port in the intermediate housing screw up any potential scavenging? Maybe both?
* - Vacuum is a funny concept, it doesn't exist other than as "pressure lower than atmospheric". Atmospheric being completely dependent on altitude and weather patterns. It's a horrible metric. So, really, if you consider the chamber pressure from a piston pushing the exhaust gases out to be "normal atmospheric", ANYTHING lower than that might be construed to be a vacuum. But for the purposes of this post we'll consider it to mean lower than 100kpa.
Maybe rotaries are different because the exhaust pulses happen so close together? Does the shared exhaust port in the intermediate housing screw up any potential scavenging? Maybe both?
* - Vacuum is a funny concept, it doesn't exist other than as "pressure lower than atmospheric". Atmospheric being completely dependent on altitude and weather patterns. It's a horrible metric. So, really, if you consider the chamber pressure from a piston pushing the exhaust gases out to be "normal atmospheric", ANYTHING lower than that might be construed to be a vacuum. But for the purposes of this post we'll consider it to mean lower than 100kpa.
01-28-23, 11:38 PM
#28
Yeah, the 13B-MSP "headers" are 3-1 with 1 of the 3 primaries shared by both rotors.
Its like having a primary exhaust cross over at the engine, because thats what it is.
Some manufacturer tried a "tanged" primary to divide the center housing port, which is great if you then make a 4-1 header, but they kept it 3-1 so they moved the exhaust crossover into the pimary where the tang ended instead of in the center exhaust port. So... a couple inches?
As far as I know no one has made a center port divided 4-1 header for the 13B-MSP.
Its like having a primary exhaust cross over at the engine, because thats what it is.
Some manufacturer tried a "tanged" primary to divide the center housing port, which is great if you then make a 4-1 header, but they kept it 3-1 so they moved the exhaust crossover into the pimary where the tang ended instead of in the center exhaust port. So... a couple inches?
As far as I know no one has made a center port divided 4-1 header for the 13B-MSP.
The following users liked this post:
peejay (01-30-23)
04-29-23, 06:58 PM
#31
235hp at the wheels @ 9000rpm. New stock unopened FD crate engine, stock injectors, stock ignition. Honda throttle body. Relatively cheap, simple NA power. This one is in a circuit race FD with a series 2 Rx8 6speed behind it.
04-30-23, 01:19 PM
#32
Junior Member
Thread Starter
05-02-23, 07:54 PM
#33
I never understand why anyone chooses that same kind of carb manifold you’re also intending to use. Those things should have be just as much in the past and long forgotten as disco dancing.
all those Renesis headers posted above failed for the same reason I posted about previously. All the exhaust tuning theory you think you know is completely out the window on a Renesis engine.
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all those Renesis headers posted above failed for the same reason I posted about previously. All the exhaust tuning theory you think you know is completely out the window on a Renesis engine.
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Last edited by TeamRX8; 05-02-23 at 08:27 PM.
05-05-23, 06:14 AM
#34
I actually own Rotaries
iTrader: (40)
235hp at the wheels? That is very impressive! Wasn't the stock FD like 255hp at the flywheel?
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