Festy dyno vid 302 hp

[bhazard]

I had to disable their "enhanced mobile view"

[shorestiva]

From a quick search on miataturbo it looks like a hx35 will hit 18 psi at 3800rpms on a 1.8

[bhearts]

From a quick search on miataturbo it looks like a hx35 will hit 18 psi at 3800rpms on a 1.8

Is that waste gated?

Sent from my SM-G900V using Tapatalk

[bhearts]

I think hx turbo would be an awesome oem option, because you know diesel shops could get them rebuilt reliably and cheaply.

Sent from my SM-G900V using Tapatalk

[sketchman]

At least one guy I know used the 35 on a Dodge Neon with the stock 2.0 and said it was a good match. I'm sure like mentioned above the BP would love it.

[shorestiva]

Yeah he was only running 18 psi total. You can't compare a bp to other motors though the bp heads don't flow that great.

[David88]

Hi

Sent from my SCH-I545 using Tapatalk

[David88]

Yes, I meant Volume. As a simple way to explain how the volumetric efficiency of a turbocharged engine is only truly understood when the entire system is looked at as a whole, rather than hyper focusing on one component (i.e. head flow rate or compressor map.)
All too often the emphasis is placed on getting air mass into a turbocharged engine, but little consideration is placed on the exit strategy.
The O.P. was discussing the difference in turbine housings and wheels (the volume of the turbine housing in particular ) when all this discussion of CFM vs. PSI broke out. Mike is on the right track with where he's going.

Sent from my SCH-I545 using Tapatalk

[David88]

Haha. Love this turbo stuff. Catching up on it on my 1st new smartphone with tapatalk. No idea what I'm doing with that either. Bit of a learning curve.


Sent from my SCH-I545 using Tapatalk

[bhearts]

Does anyone have experience with professional rebuilds of oem turbos?

Sent from my SM-G900V using Tapatalk

[Advancedynamix]

The HX35 works on a 1.8 engine, but it's not a good match. To understand why you'll need to think about how turbochargers make boost, and how that boost works inside the engine.
Boost pressure with a centrifugal compressor is accomplished by inertia of rapidly accelerated air molecules. Using too large of a turbo will result in a violent boost curve. When the engine finally makes the exhaust energy necessary to spin the turbo fast enough, it is then confronted by a massive amount of air. When I was first getting into turbo engines I thought it was cool to have a boost curve that dumped massive amounts of air at the same time as the engines natural torque peak. This feels incredibly fast, and makes big numbers on a DynoJet dyno. What I came to learn though, is that it's not actually fast, it's destructive. The violent boost spike makes TQ that is hard to put to the ground. I got tired of replacing transmissions and being passed by cars with properly sized turbochargers. Now, when I drive a car with an excessively large turbo I get frustrated because the power is hard to use, and inconsistent. It's not hard to use because it makes too much power, it's hard to use because it makes unfavorable power. I like to go fast, not feel like I'm going fast when I'm just breaking things. Lol
The gt35r is a better choice than an HX35. I hope this China charger works like a real gt35.

[bhazard]

That's what I'm afraid of. Though my automatic trans might smooth it out a bit. Could a boost controller help smooth out the power?

[Advancedynamix]

Yeah, the trick with a large turbo is to use it together with a large external wastegate and a way to control the boost with a tunable map (controlled with a tunable engine management system).
Typically, you'd build an engine like this with a higher compression ratio, and tune the system to come on slowly at high rpm. The cam profile and port shape would be tuned for low to midrange power, and the turbo would work to broaden the usable TQ range. An engine like this can be tuned to have a very broad, usable power curve, but this takes a lot more planning and a very well designed exhaust manifold to work smoothly. The Festiva is a perfect car to build this type of setup, because it requires very little TQ to be fast. The BP in it's stock form is not a good engine choice though. Usually you would want an engine which could be reliably pushed to at least 8500rpm. If you push a BP hard at those revs for long you'll shatter things. The engines rod ratio is not correct for this type of job. If you destroked a BP about 12mm and increased the rod length 12mm, you'd have a stable and bulletproof engine that could be used to 8500rpm.
With a peak TQ around 5600 rpm and a turbo that doesn't become efficient until 4500rpm, you can see why this setup produces a short power spike. Your better off with a turbo that is most efficient at 3500rpm (crankshaft rpm, obviously not turbine rpm) which would give a smooth and broad tq curve.
You can spend all afternoon comparing turbine and compressor flow maps with the theoretical needs of your engine, but I find it much more effective to just study the results of similar setups with different chargers. Even the turbo manufacturer will admit that the maps are theoretical, and subject to many variables. The dyno, and racetrack are the only true way to be sure what works. We are lucky to live in a time where dyno graphs are commonly published by enthusiasts. Just be leary of any DynoJet graphs as a DynoJet is not an accurate way to measure power. Also, don't look at a dynograph for ultimate numbers, instead pay attention to the way the engine delivers TQ. This can be difficult to compare because graph scaling will be different from one test to the next.

[bhearts]

I think it'd be super cool to run a whole car length wastegate pipe. Have it come out the back by the turbo exhaust pipe

Sent from my SM-G900V using Tapatalk

[Dragonhealer]

I think it'd be super cool to run a whole car length wastegate pipe. Have it come out the back by the turbo exhaust pipe

Sent from my SM-G900V using Tapatalk

That's the way we did marine turbo diesels in the military......