j9fd3s

iTrader: (3)

no prob. i see you're still using the metering oil pump?

mike

RICE RACING

Yup! I run that + 200:1 premix (due to extra stress engine is under), front cover is converted to run mechanical OMP (12A Turbo) works well. Thinking seriously of pulling it out and putting in a PP though since I drive it very rarley on the road anymore and I do have a daily driver/tow vehicle now

I love PP's but I remember how much I hated them too (noisy, ridiculous fuel economy, go like **** when restricted) ! Good old love/hate thing going on in my head

shinjuku

Hey Pete for the pressure wave tuning calcs do you treat the turbo end as an opened ended pipe or closed?

BTW that manifold looks very nice cant wait to see the rest of it!!

Isnt the exhaust wheel a bit small?.......

RICE RACING

LOL yeah

It's bigger than a Greddy T88 Turbine!, much bigger than the HKS T51 turbines (SPL & KAI).

It measures 78mm at the minor dia, that combined with a 1.22a/r should flow reasonable enough sized the WG so it will by pass no more than 30% of the mass flow through the engine so Ex manifold to In manifold pressure ratio will be quite low & well below 1 with the right exhaust system.

RICE RACING

Enzo tell me about it!!!

I found this out with my older style manifolds, the new one has a lot of detail that does not come out in the photo's but at the junction of the WG pipes the angle is shallow and the entries are eliptical in shape allowing a good length of time to establish flow into the WG runners, along with all of that the junctions are at points near "branches" that deflect some of the exhaust gas to the WG. See how she goes soon enough

turbo-rotary

Thanks for the pics Rice. We are building the manifold here shortly. I will post pics when we get done.

J Oliver

It was a 13BRE Cosmo engine with a large race/street port. As soon as I changed turbos the whole setup just came alive. It was a night and day difference. The turbo you have (same as what mine was) looks big and awsome but it just does not spool very well. You might get around that with manifold design but I just wanted to let you know what I went through so you could have a different option.

Turblown

iTrader: (12)

That manifold looks nice Rice Racing, any plans to duplicate it? What are you ideas for a 3 rotor manifold?

600HP CLUB

so when i build me my manifold, i should do the manifold to wastegate ( to make the wastegate to be directly in the way of the gas pulses) then build the turbo to wastegate runners, would that be better to control the boost? it'll be alot of restriction to the turbo, but the control should be great right?

600HP CLUB

this pic is weak but i'm thinking of something like this.

BDC

True. The Cosmo 13BRE has significantly larger port runners than the 13BT but this engine we're working with has a large extend port plus two bridgeport cuts. On the two cuts alone, we saw a difference of 70ft/lbs of torque and the same HP with 3-4psi less boost. This engine will move the air; the exhaust (manifold) just needs to be setup differently in my opinion.

B

fdracer

your primaries still need to feed directly into the turbo and your wg is branched off of that.

RICE RACING

I hope to make quite a few when time permits .

In regards to three rotors, its hard!!! tuned pipes are great for the equal performance of each rotor, but the energy loss of the pulse before the turbine wheel is still hard to overcome.

This is why it is fantastic if you can either run a single turbo for each rotor or a turbo that has a divided housing which will make the most of the "free" energy.

There is not much you can do? Just make them equal length but still you will need to run a smaller exhaust housing because you will not be able to harness the power of the pulse to full effect as it is being "dilluted" before it hits the exhaust wheel.

It realy is amazing how big a turbine can be run when you use the exhaust pulsing to it's full potential, this same principle can be applied to straight 4 cyl engines where groups of two cylinders fire at once and each pair is fed into each seperate runner of the exhaust housing, the turbine combination I am using worked great on a 4cyl 1.5lt engine which reved to 10000rpm (power band from 6500 to 10000rpm) max, so with 2.6lt and 9000rpm plus stronger pulsing of a rotary there realy is no problems.

On a side note to BDC, I saw a piston example of the problem you are facing. this guy put on a fairly large divided housing turbo and the thing would only start to make boost in second gear and reach 10psi in 3rd!!! He swaped it out for a tuned split pulse header (grouped 1&4 and 2&3 into each runner of the turbo)and the thing started to hit full boost in first gear !!!!

It makes a massive difference and only some engines is it possible to be used to full effect, of which a 13B is one....so use the power thats there, its FREE and it will be a totaly different machine, you get the benifit of using a low restriction/pressure turbine combination while retaing the instant responce offered by harnesing the power of exhaust pulses to full effect

87GTR

iTrader: (61)

Rice Racing I just want to say thanks for all this great info your sharing with us.

Turblown

iTrader: (12)

Yea its hard to come by such great advice, especially for free.. Thxs

50tooslow

Rice what are your thoughts on running two smaller dual ballbearing turbos? Would this be benificial vs. running 1 large turbo.
nick

HWO

that would cost you 4 times the price of a normal T04 sized beasty, and i very much doubt that the gains to be found would offset the extra expense

RICE RACING

My personal feeling is that this is the ultimate set up having one seperate system (turbocharger & WG) per rotor is the ideal.

The problems are numerous though, assosiated plumbing of exhaust and intake delivery and discharge pipes could very well negate some of the performance gains, though spool rate at lower revs would be better for sure due to lower inertia associated with two smaller units.

The plumbing is a major nightmare and side issues related to heat shielding and inadequate space would become real issues that would reduce the performance of this set up compared to a well layed out large single turbo, it is very easy to loose gains by having to have a very tight series of bends to fit in a DP just as many bends to fit in the discharge pipes + have air filters located of convoluted pipes going to the compressor intakes, all of these things cause pressure drops and loss of efficiency and performance, not to mention the heat build up and radiated heat to other components increasing heat soak and further decreasing performance. Every twin "single" turbo set up I have seen in an RX7 engine bay has been a massive compromise and a non ideal situation with one or more elements having to be compromised.

I looked long and hard at doing this myself, and I chose to do the very large single for my target range of engine operation 5.5k to 9.5k rpm it will be just as responsive as a twin set up, and will be more efficient.

On a side note, this same issue was struck by F1 4 cyl engine runners in the early to mid 80's Hart, BMW, Zakspeed, The majority of which most chose to use a large single after trying to install the twin set ups in a chassis and experiencing heat realted issues, and performance losses due to the reasons I eluded to above, they got over the responce issue of a massive single by using the optimum header design which helped a great deal. The only one to try twins on the 4cyl was Alfa Romeo and the engine was a disaster, the prototype car actually burnt to the ground in one test session and it never actually raced. There are other good references to how much benifit a group split pulse tuned header works, there is a good old book called "turbochargers" by Hugh McInnes and in it they detail a BMW engine that was the precursor to the BMW F1 4cyl turbo engine and the differences between running a simple log manifold and running a manifold like we have been talking about, the differences as noted by McLaren engines was amazing!!! The engine went from having quite large lag to being virtually non existant simply by using the power of grouped pulses to increase turbine resonce, they noticed a VERY large increase in power too.

I know people hate refering to the 13B like a Inline 4cyl but as far as the basics go the same principles can be used (exhaust pulsing) and even greater effect on a rotary as there is more energy available

Twins technically are the ultimate, in practise there are many issues that will make it hard to realise the full potential.

HWO

in a rear engined space framed type car i would think it would be achieveable as far as space goes

RICE RACING

Exert from the book Turbochargers. Page 112 Intake & Exhaust Tuning

Basic summary of log manifold v's tuned length header on BMW 4 cyl 2.0L IMSA Engine of very ealry 80's.

Log manifold = 540bhp
Tuned headers = 600bhp

"Gary went on to experiment with axially divided turbine housings, an available option from most turbocharger manufacturers, he found that if the exhaust pipes were connected to the seperate sides of the divided exhaust housing so the exhaust pulses entering each side were evenly spaced, throttle responce improved even more. though this arrangement did not add power (over the tuned header v's the log) "turbo lag" was all but gone"

They go on to descibe how a similar principle is used by some road racing V8 engines but due to their firing order need to have pipes going all over (from left to right banks of cylinders) the place to achieve the even pulse spacing to use a divided exhaust housing to it's greatest advantage.........go on to say that some of the worlds quickest road racing cars use this arrangment to improve response out of low speed turns.

I think the key thing here is try to make the pipes the same length and keep the front and rear rotor pipes seperate into either side of the divided housing and you will have fantastic results, with minimal "lag" to boot

enzo250

Peter is absolutely right. I have built many turbo headers for 4cyl engines and you would be surprised how big of a turbo we could use when the turbo has a divided housing and the header groups cyl's 1&4 and 2&3 together into the housing.

I will be building a header for my rotary soon and will use a divided housing to help spool my monster.

Here are some pics

enzo250

Here's one of the exhaust housing. It's a 1.15 a/r

Peter: what size wastegate are you running?

i was thinking of using two 40mm tials or one 46mm.

setzep

he is using a 46mm

carx7

iTrader: (31)

Let me ask this question. If for example the desired turbo isn't available with a divided housing, would fully divided manifold with equal lengh runners etc benfit the turbo. Or does not have a divided turbine housing ruin any and all benefits of keeping the pulses divided for the length of the manifold?

My hunch says this would be better than a collected unequal mani, but can any one verify this?

RICE RACING

Read the BMW example 540bhp v's 600bhp LOG v's Tuned......then they go on to divided to eliminate/minimize "lag"