CanadaFI

Hey Guys,

Hope im not recovering a subject that has been discussed before, but I searched high and low and could not find many answers.

Alright, so heres the deal.

Ive got a 2005 Mazda RX8 with a 5.3L L33 in it. Its a T56, stock N/A Setup in it right now to make sure the swap would even be a nice to drive car etc, but now I am completely hooked on Time Attack racing, and I will be selling alot of my swap parts out of it, to refab and make a more dedicated track car.





Heres where I am looking for some opinions.

Im on the fence right now between trying to put cash together for a 500ish HP N/A LS2 or LS3, or to design a turbo kit and boost the 5.3L. I would prefer to go the boost route, as I am looking for a new fabrication challenge for the car. Supercharged is also an option, but costly. I have more time then money lol.

For time attack, my power under the curve is very important, just as my spool up times. I know I will have to be very detailed in how I design the kit.


Im looking at doing a single front mount TC78, and aiming for about 600whp, unless I can find some extremely small framed turbo's with enough of a punch, as I could tuck something very small down beside the motor similar to the APS systems for the corvette, but I havent had much luck finding information on sizing for small frame turbos to measure out the car and see if they would fit.

I have looked at a ton of TC78 5.3L dyno graphs, and it seems to leave a bit to be desired in regards to power curve, with power hitting hard above 3500rpm for most builds.

Do you guys have any input for helping get the turbo online earlier, and it staying in power longer? different turbo maybe work better? I have thought about twin wastegates to help keep it spinning up over 6000rpm without drive pressure going through the roof.

The big downside to the single front mount is all the extra weight on the front end of the car, which is where the small twins would be nicer to fit some weight behind the axle centerline.

Appreciate all the help guys, working on sorting out first whether to go tiny twins (if budget allows) or the single front mount, and then I have to figure out how to get a good powerband out of the engine so that I am not crashing coming out of corners when the power slams into it.

It will be set with a 3.73 rear gear and T56.

FourG63 97GST

iTrader: (1)

Don't over turbo, for that type of racing you don't want quick small and low end torque.
I believe I've accomplished what you're going for a billet PT6775 .96 on a 5.7 though.
I'll stay in that range

stevieturbo

For low mounts, small turbos etc, the AGP twin turbo stuff for the Gen5 always looks good.

Whether it will physically fit, who knows, but it's certainly something to look towards.

http://www.camaro5.com/forums/search...rchid=29757068

http://www.camaro5.com/forums/attach...1&d=1379277124

I'd doubt you would have as much ground clearance as the Gen5's though, but still take a look.

http://www.camaro5.com/forums/showthread.php?t=288657

I did similar using truck manifolds, and managed to keep the turbos in very tight to the engine/bellhousing with almost nothing lower than the oil pan itself ( F-Body type pan )

That said, with only a 600hp goal, I'd nearly be inclined to suggest a centrifugal supercharger.

The Alchemist

iTrader: (19)

The turbo guys can chime in, but I too like spirited driving in the twisties, and I really like the positive response of the procharger with the 6-speed. Power is instant coming out of corners, where I'd be concerned with how a turbo would have to react going on/off/on throttle transitions.... again, I don't have experience with a turbo and a 6-speed and powering through twisties, but that would be something I would look at.

Try to find someone with a 6-speed and a turbo and if you know them well enough, ask to drive it and see for yourself how it responds to your throttle input. I love how my power delivery is very linear, and not 'snappy' like a turbo. Turbo guys will tell you that power delivery can be like an on/off switch, which may upset a car in a corner if you were to roll back into the throttle and have it go from vacuum to max boost in a few hundred rpm.

stevieturbo

Turbo boost will be how you design and build it into the system, but it will never respond like a supercharger.
But certainly whether road or track, a turbo setup can work very well

600hp is a relatively low goal, and will require small turbos so they should be very responsive. But a centri at that level would be excellent too.

Turbo power delivery is only snappy or excessive torque, if you allow it to be like that. With some half decent boost control and a well designed setup, it should be very safe and controllable.
Obviously if you design it badly and dont know how to set it up...then yes it could easily be a handful. We dont live in the dark ages now, there are so many options for control out there though

gnx7

iTrader: (28)

unless you are prepared to run an a/w intercooler inside the car or somewhere not blocking a fresh source of air to the radiator you are going to run into overheating issues doing an a/a intercooler unless you did some sort of V mount setup. It would need to be a very well thought out system to not have these issues... or run very low boost.

This idea has crossed my mind many many times... and I have a stroker LS motor instead for reliability and less issues to chase. A stock LS2 bottom end with stock LS3 heads/intake can easily make 525flywheel HP. That is what the new owner of my old FD road race car ran (460rwhp) and he set some track records out here on the west coast in his Unlimited class (2470lbs and 320/18's all corners). At that point you need 13" quality big brakes, oil cooler(s), and ducted radiator just to keep that cool.

Unless your 5.3 is an alum block I feel you would benefit more with going to an alum block to shave 80lbs+ then adding another 50lbs of turbo/intercooler up front.

The turbo RX-7 car I have run a radiator up front and a small one out back. while it has no issues keeping it cool after a 1/2 mile pass.... continual 20-30 min sessions would take it toll and I don't think it would stay cool. I run an a/a setup in front of the radiator.

Remember more power means you need to do a diff cooler as well or you will cook it due to its tiny capacity.

Do you have big brakes on the car currently?
what kind of budget do you have to work with?
Do you have a welder or access to one?

chuntington101

What that much power why not just stick a Eforce on there? would they fit the 5.3?

Would add a fair old bit of weight but then so will a centri or turbo. But will give you instant boost and should fit in there (about 2 inch taller than the stock intake I think).

or as gnx7 said why not just buy a built NA motor and run that. then you keep the weight out and still get decent power.

ddnspider

iTrader: (26)

I was waiting for a post about a positive displacement blower as that was what was going through my head. My only concern would be they tend to skyrocket IAT's the longer they're running at full tilt, so I would assume heat soak would be a significant concern.

chuntington101

That's always an issue with any form of FI. However it is more true with PD blowers I think. You need to ensure you have sufficient low temperature heat exchangers (HEs) to cool the water for the superchargers intercooler(s).

The great thing about using air to water is you can mount the HEs were you want. I have seen a gt500 that had a large one mounted in the trunk off the car and the another large HE at the front. He pipes water to the rear one first and then through the front one. This also reduces the impact of the front HE as the water has already been cooled before it gets to the front HE.

It's also worth looking at the water paths and removing any restriction you can. The ZR1 guys for example use new water manifolds that help reduce the restriction of the stock unit.

Like any system they can be engineered to work really well and the great thing is the packaging.

stevieturbo

From a simplicity point of view, if you only want 600hp, just stick a n/a 427 or something similar in it

LS1-IROC

iTrader: (4)

You can manage the heat with a PD blower. You just have to do some homework. That's the route I would go in your case for predictable power....or go big cube N/A.

CanadaFI

Thanks for the input guys! (I am having trouble getting my replies to show up here)

The 5.3L is the aluminum L33.

I have thought about a centri setup, but mainly looking away due to cost and having the same weight infront of the axle issue as a turbo, so If I am going to go that route, I would prefer to go turbo.

Part of the reason I want to turbo it, is the challenge of designing/fabricating/tuning a responsive and useful turbo setup for time attack.

I hadnt thought about the A2W intercooler, but your right about needing to keep a lid on engine bay temps, though I will be running a vented hood to extract heat.

As far as chassis setup, I do have a welder that I am very good with (fabricated all mounting, headers etc in my car right now), and it will be getting CTS-V Brembo 4 pot's on it to bring it down as I am already melting Hawk HP+ pads with just a stock L33 in it right now at my local track.

I know a N/A setup would be more reliable, better balance, and better heat control, but I already built a N/A one, and Im bored of the car already

Here is a few turbo's I have been looking at. I read mostly good things on the CXRacing turbo's now, the nice thing is for the price their a ballbearing billet turbo. Otherwise I have been looking Turbonetics.

I would set these up with dual wastegates and spent 10x more time designing the kit then fabricating it as I know going with too small of a turbo to get boost online quick will be a challenge elsewhere.

Heres what I've been eyeing so far:

http://www.cxracing.com/mm5/merchant...ory_Code=TRBT4

http://www.cxracing.com/mm5/merchant...ory_Code=TRBT4

https://turboneticsinc.com/store/ind...&product_id=81

https://turboneticsinc.com/store/ind...&product_id=80

Thanks for all the input guys!

stevieturbo

So...you dont want the weight, yet you do want the heaviest option which is a turbo ?

You dont want the heat...and the turbo is probably the hottest option ?

And either centri or turbo will all add weight out front, unless you use some form of chargecooling mounted at the rear....which will then incur more weight from plumbing, and if A2W more weight from water and pumps.

Really, the lightest form of boost you will use, is a centrifugal supercharger.

The lightest overall, will be an all alloy 427 if you can arrange that, and it means no charge cooling or turbo heat to worry about.

And if you want super responsive to the throttle, then there is no question, the centri is the better option.

Everything you are wanting, a centri is the best choice.

CanadaFI

In a perfect world, I dont want weight and heat. What I do want more then my concern for that, is a fabricating challenge. It currently weighs 2900lb (53.5/46.5 F/R balance), and will be having alot of weight removed from it this winter, I imagine about 26-2700lb starting point, with a goal to stay under 3000lb.

Unfortunately a 427 NA setup is out of the question as that is pretty far out of my budget.

I have assembled and worked with many centrifugal supercharged LS, and also turbo LS motors, but all were just fast street/drag cars.

As far as Centri's, Ive used the D-1SC, F-1A, Novi 2000 and V-7 YSi, each were insane with power ability. D-1SC is probably closest in line with what I am looking for, the only thing is I would have to get very creative with fitting it onto the front of my engine, and getting a air inlet tube onto it.

The engine bay on my RX8 is a fairly tight space, though there is definitely turbo room as I have more location freedom from it.

On the note of the extra weight of a A2W cooler, in opinions of the more experienced guys on here, would the benefits of it out weigh the extra weight of it in regards to heat soak?

Appreciate the input. If I were to go the turbo route, I'm trying to figure out all of the variables to make it effective, as I know a centri would be the best option. If I go centri, I have a pretty good idea of how I would set it up, thats why I was looking for some input on the turbo route. I am aware of the limitations I am up against with a turbo.

stevieturbo

The only limitation are the ones you create.

And I would never build a forced induction setup without at worst...a very good charge cooling setup regardless of what weight it might add.

CanadaFI

Wise words!

Thanks for all your advice! Appreciate it!

Going to do some number crunching and idea planning tonight to see what I can come up with for a turbo system. Plan B is centri

chuntington101

If you went twin turbo you could mount the turbos low down and far back in the chassis. You could do a cabin mounted chargecooler and even a rear mounted HE.

Key think with a water to air setup is getting enough HE. Most just stick a big thing up front but that's not always the best. A ducted rear mounted setup would work really well and could be sized pretty large. You could still run a smaller HE up front to ensure temps are as low as you can get. I have seen this done very well on a GT500.

Alternatively you could mount the engine rad in the rear and run a nice large a2a cooler . This would probably be lighter overall and should work well.

Thinking about it if you are only after 600bhp could you not do a single low mount setup with a cross over? This would give you room to grow (ie go to a twin setup) later is required and keep the weight low in the chassis.

Just some ideas.

Forcefed86

iTrader: (4)

Heads, cam, exh, intake on the 5.3 will make over 500 hp on the 5.3. Mount two 20lbs nitrous bottles in the trunk and go to town. 50hp out of each corner 100ish through the straights would work well.

Turbo Heat management is a PITA and gets expensive when road racing.

97WS6SCharged

iTrader: (1)

Probably going to get scoffed at for this one but why not build a rear mounted turbo setup? It would keep more of the weight over the rear tires instead of the front as well as prevent some of the additional heat built up that a front mounted setup would produce. It would also simplify fabrication since, presumably, you already have headers and an exhaust on the car. And even if you add 30-50 lbs to the car the additional power from the turbo will more than make up for it.

ddnspider

iTrader: (26)

Headers and exhaust usually make a rear mount turbo slower. There's been a ton of threads on the subject. And they spool slower than a traditional front mount setup given equal precautions taken (header wrap, good tune, etc.) He would have to under size his turbo for a fast spooling rear mount setup.