is 10psi from an mp62 more stress than say 10psi from a gt28rs? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 07-08-2007, 07:18 PM   #1
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Default is 10psi from an mp62 more stress than say 10psi from a gt28rs?

My buddy has a good tune on a built motor with 10psi from an mp62, and goes through like 1 motor per year. He drives the car really, really ******* hard at the track. He had the car tuned with no knock, 11.5:1, and it felt great and dyno'd 230whp.

I don't see why his **** keeps crapping out. All I can think of is a ****-ton of parasitic loss, and enough flow at 10spi to make that power.
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Old 07-08-2007, 07:21 PM   #2
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Isn't the MP62 a smaller blower. It still might be moving more CFM at 10 psi than a GT28RS, I'm not sure where to get flow info on the MP62 though.
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Old 07-08-2007, 07:27 PM   #3
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Originally Posted by cjernigan View Post
Isn't the MP62 a smaller blower. It still might be moving more CFM at 10 psi than a GT28RS, I'm not sure where to get flow info on the MP62 though.
Its supposed to be the big miata blower. I don't understand why everyone around here has such a hard time with FI cars.
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Old 07-08-2007, 07:36 PM   #4
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All I can think of is a ****-ton of parasitic loss, and enough flow at 10spi to make that power.
How does Parasitic loss end up killing motors? IIRC isnt Parasitic loss dealing with draining power from your battery cus something doesnt turn off all the way and draws anything other like .05 amps from the battery even when the car is off.

*EDIT* and even if your talking about Drive train power loss I don't see how that will end up killing engines either...
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Old 07-08-2007, 07:39 PM   #5
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Originally Posted by LunaticDriver View Post
How does Parasitic loss end up killing motors? IIRC isnt Parasitic loss dealing with draining power from your battery cus something doesnt turn off all the way and draws anything other like .05 amps from the battery even when the car is off.
I postulate that the parasitic loss is so great that more flow is required to produce the given power level in respect to a turbo car. I wasn't trying to open up the classic, ------ supercharger / turbo debate...I need to find a compressor/blower map for the mp62.
mp62:

gt28rs compressor map:


I don't know how to compare this data.
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Old 07-08-2007, 07:47 PM   #6
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I postulate that the parasitic loss is so great that more flow is required to produce the given power level in respect to a turbo car. I wasn't trying to open up the classic, ------ supercharger / turbo debate...I need to find a compressor/blower map for the mp62.
mp62:

gt28rs compressor map:


I don't know how to compare this data.


I dont even know how to read either of those... but I get what type of parasitic loss your speaking of.... as for the answer i have no ******* clue
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Old 07-08-2007, 07:59 PM   #7
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Originally Posted by LunaticDriver View Post
I dont even know how to read either of those... but I get what type of parasitic loss your speaking of.... as for the answer i have no ******* clue
well, it looks like it takes 20crank ponies...so roughly 25whp to drive the blower at 7500rpm...so at least we have that to estimate...but how much exhaust does it take to spin the turbo at that rpm, and what does that translate into for hp on the turbo car?
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Old 07-08-2007, 08:35 PM   #8
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I run 11.4 PSI on a completely stock motor. Your friend is doing something wrong if he's going through a "built" motor at only 10 PSI.

I'd have to guess and say that his cooling system and his oil is not doing what it's supposed to and it's overheating the motor.

Has he ever torn the motor apart to find out the cause?
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Old 07-08-2007, 09:24 PM   #9
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wouldn't the SCer be less torquey to boot?
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Old 07-08-2007, 11:15 PM   #10
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I run 11.4 PSI on a completely stock motor. Your friend is doing something wrong if he's going through a "built" motor at only 10 PSI.

I'd have to guess and say that his cooling system and his oil is not doing what it's supposed to and it's overheating the motor.

Has he ever torn the motor apart to find out the cause?
It looks like an exhaust valve is toast. He has an intercooler and a 37mm pwr radiator...if the gauges indicated a problem he would shut it down.

The guy knows exponentially more about me than miatas, but I think something is wrong since he's going through roughly one motor per year. The car gets bimonthly track beatings...the guy drives super hard.
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Old 07-08-2007, 11:23 PM   #11
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Originally Posted by hustler View Post
The guy knows exponentially more about me than miatas
:gay:

heh. well then be glad he isn't asking for help with his rear end.

seriously though, that's not enough boost to be popping a motor. there just has to be something else wrong with his setup.
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Old 07-09-2007, 12:19 AM   #12
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whoa 180F charge temps? tell him to intercool that bitch.
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Old 07-09-2007, 01:48 AM   #13
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These Devils Own kits ******* rock on PD charger setups.
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Old 07-09-2007, 04:21 AM   #14
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His IC is most likely to small and he is borderline when on the track, or the drag from the SC is causing the Timming belt to slip ever so slightly, letting the valve hang and get burned up. Is his motor built with oversized stainless valves, and forged pistons, hell what kinda springs is he running if say he puts 10K miles on his car at 6800+ rpm then that is alot of wear on the valve train and i would think of upgrading. The stress of 6800 rpm continuos like that is probably what is killing his motors. Look at nascar they run 9K rpm full out for 300 miles or so and there motors begin to eat themselves.
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Old 07-09-2007, 09:31 AM   #15
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Personally, I think that blowers are harder on motors. There is an extra pulley to turn, and the whole thing of parasitic loss, it takes power to make power. I would wager it takes 35hp to turn that blower at full boost at X rpms. Turbos are way more efficient in that aspect. My blower made the steering feel heavy, you dont realize it until the blower is removed.

My car is stock now...I am collecting parts, so the turbo build will come within the next month or so.
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Old 07-09-2007, 09:52 AM   #16
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Originally Posted by 96rdstr View Post
Personally, I think that blowers are harder on motors. There is an extra pulley to turn, and the whole thing of parasitic loss, it takes power to make power.
Yes, because turbos provide free power, right?:gay:

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My blower made the steering feel heavy, you dont realize it until the blower is removed.
Not really sure how that is possible unless your power steering pulley was slipping after installing the supercharger.
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Old 07-09-2007, 10:05 AM   #17
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Originally Posted by y8s View Post
whoa 180F charge temps? tell him to intercool that bitch.

Didn't even think about IAT temps. I also notice 95% of the threads on SCers at M.net is about pinging with base kits.
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Old 07-09-2007, 10:08 AM   #18
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the 180* temp thing is from the magnussen site, not his car.
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Old 07-09-2007, 10:30 AM   #19
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right that is the stock delta T of the blower so he could see pre IC temps of closer to 250-300 degrees factoring in the ambient under hood temps.
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Old 07-09-2007, 10:32 AM   #20
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The issue is probably a combo of heat from the blower heating the charge.... and then not having it go anywhere...

The TDR is great for temp differenial on the intake temps, but... you can still heat the blower when pushing it really hard, so I know a guy who cooked the bearings in the back with 14 or 16psi on the track. He had to run WI into the blower, to help keep the casing/rotors, and such like cool.

Plus, it sounds like from a toasted exhaust vavle, that he's probably needs to do a dual feed rail.

I think the biggest issue with the SC kits, is not the blower itself, but that a lot of people try to turn the boost up, without doing the rest of the required mods to run on the track == dual feed rail, oil cooler, re-route, etc..... I get the impression, that a lot of the tracking turbo guys seem to do more to prevent the heat from the get go.

Also, it might be what fueling solution too.... a lot of the blowers are coming with just the marginal fuel mods -- like the PC or PC Pro (which is at least adjustable -- well sort of). Most don't step up to something like an MS.....

I've found an improvement running with the EM-B..... But before this car hits the track, even with only the 7.5psi.... I'm need an IC. I'm not going to risk the changes in the intake temps, when pushing it. Before the boost goes up, the rest of the stuff has to get done -- IC, oil cooler, etc......

Dave,
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