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-   -   Turbo Bridgeport discussion (https://www.rx8club.com/series-i-major-horsepower-upgrades-93/turbo-bridgeport-discussion-263707/)

Brettus 10-22-2016 04:57 AM

Turbo Bridgeport discussion
 
Been trying to work out why my Turbo Renesis Bridgeport is so ineffective ........yet we see such huge gains on PP engines .
My theory :

On the Renesis the only VE gain that can be had seems to be in replacing the carried over exhaust gases with intake air . Looking at the chamber at that point in it's cycle, it looks like somewhere around 5% of the total swept area . So a maximum gain of that magnitude is possible. Looking at my results so far , i may be getting close to these gains , but nowhere near what a PP engine achieves.

So I started to think about why such big gains are possible on PP engines .
I haven't seen any discussion on this so I don't know what explanations have come forward from the 7 guys.
The Peripheral port stays open way longer than the renesis side port and therefore allows much more air to flow through it ...it keeps flowing after the chamber has compressed the exhaust gas .
I'm actually thinking the gains are being made ..............outside of the engine . What if the intake air goes straight through the engine and into the exhaust . The fuel then ignites creating combustion just before the turbo . This creates more heat and pressure outside of the engine ..similar to antilag!Result is turbo is spooled up in part by this .... meaning the engine doesn't have to do it . Result = more power .

Just a theory ... anyone else got any ideas on this ?
Cough ...Teamrx8 ?

sinkas 10-22-2016 06:06 AM

Seems reasonable
Does anyone know what the point if the side exhaust ports was supposed to do,?minimize overlap?

reddozen 10-22-2016 09:48 AM

Brettus,
I think my bridge is coming out around the first of the year. After 80k miles, it's time for something new. If I can work out a couple bugs in the tune this weekend, I'll dyno it next weekend at a local event.


Originally Posted by sinkas (Post 4787692)
Seems reasonable
Does anyone know what the point if the side exhaust ports was supposed to do,?minimize overlap?

Side exhaust allows for zero overlap, and lower emissions from the factory setup. Not great for power gains or engine longevity (in it's renesis form).

dannobre 10-22-2016 12:52 PM

I think a lot of things are going on. PP intakes tend to allow better charge homogenization and the A/F mixture will be more uniform. There seems to be a big difference in injector sizes and balancing Pri and Sec airflow and fuel addition...if you get it wrong there seems to be power left on the table. The shape of the combustion chamber makes this a lot more critical than in piston engines. Looking at the gains in piston engine combustion chamber shape and charge stratification made in Mazdas SkyActive engines that allows more power with less fuel.

I still think that the major issue with the Renesis is Exhaust side flow......and Heat retention

Brettus 10-22-2016 03:05 PM


Originally Posted by dannobre (Post 4787713)
I think a lot of things are going on. PP intakes tend to allow better charge homogenization and the A/F mixture will be more uniform. There seems to be a big difference in injector sizes and balancing Pri and Sec airflow and fuel addition...if you get it wrong there seems to be power left on the table. The shape of the combustion chamber makes this a lot more critical than in piston engines. Looking at the gains in piston engine combustion chamber shape and charge stratification made in Mazdas SkyActive engines that allows more power with less fuel.

I still think that the major issue with the Renesis is Exhaust side flow......and Heat retention

I would agree with you if we were talking solely about peak power . But many of the PP BP engines I have observed make huge torque in the midrange , way out of proportion with the theoretical VE that sized engine should be capable of .
My Renesis doesn't do this even though the exhaust size isn't really a restriction at that point .
If you saw my initial Renesis BP results at 10 psi ...It was actually looking quite promising as the engine was flowing way more air than a normal engine would at 10psi . If my theory were correct my engine should have made more power at 10psi than it did before the BP . It didn't .............. BUT , with my manifold design , all of the extra flow would be flowing straight through the wastegate . There is no opportunity for it to have the effect I suggested above .
So , this actually adds weight to above theory.

lastphaseofthis 10-22-2016 04:40 PM

i dont recall seeing pp renesis>? not turbo'd?

Brettus 10-22-2016 09:20 PM


Originally Posted by lastphaseofthis (Post 4787729)
i dont recall seeing pp renesis>? not turbo'd?

wut ?

lastphaseofthis 10-27-2016 08:34 AM


Originally Posted by Brettus (Post 4787743)
wut ?


Originally Posted by dannobre
PP intakes tend to allow better charge homogenization and the A/F mixture will be more uniform

peri ports.. i didnt think anyone had complete a peri port renesis... besides the guy that did like 260 n/a

Brettus 10-27-2016 01:52 PM


Originally Posted by lastphaseofthis (Post 4788549)
peri ports.. i didnt think anyone had complete a peri port renesis... besides the guy that did like 260 n/a

Dan was talking about a normal PP .... not a Renesis hybrid.


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