6266 bb anyone,or just me?
- Thread starter earcher1
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- Jan 18, 2011
Yea ..a lot of good info in this thread, not too many like this nowadays.
turbo96max
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- Jun 6, 2007
Great read. A few things come to mind based on Bisons input. Like the 6265/66 will flow up to 78 lbs/min but is this already out of efficiency range? Am I thinking about it the right way is there a flow number before 78 lbs where the 6466 or 6766 becomes a more effective and efficient option? Air temps etc??
That is max flow. You won't see that flow potential on a low CR engine or with 93/alky and even further you won't see it if there's any excess overlap. A 10:1 engine with the correct cam timing could probably squeak out 80lbs/min. I got to about 72lbs/min on an MFS 62 with 8.3:1 CR, off the shelf cam, and 93/alky on a stock shortblock in decent air. It was pretty much all in. Air was decent but not record breaking.
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turbo96max
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- Jun 6, 2007
Was there any air temps logged in the testing or other efficiency factors? Like would an mfs 64 or 67 have supplied the same air flow with less temps ? I'm kinda wondering why not just run the smaller compressor all out period vs buying something bigger if the most important factor is max flow?
I logged the manifold temps and pressures and in the last year the drive pressures. The 62cea ran out of compressor and produced high inlet temps when I tried to get more out of it by further increasing boost. It wasn't turbine limited. Id expect a larger compressor turbine to produce the same mass flow with less drive pressure which would have a big impact on the potential mass flow at the levels I ran at. I would not rec a 62 compressor for a 9 sec application. Low 10's yes. If you read what people post here and you were to take their engines apart and start measuring everything you'd find they all have very similar CR and cam timing. Even through they might not even know it. This is why they get a similar result with the same turbo. Most seem to hit 55-60lbs/min with iron heads and boost mid 20's with a 62 compressor. That's high to mid 10's typically with below average 60' times. Seeing that they usually have no clue as to what is going on in the engine the turbo is the easiest to change.
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turbo96max
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- Jun 6, 2007
Since the turbine was not done yet would you have expected better results from say a tangental 4 bolt .58/.68 housing or perhaps a h-compressor cover? You mentioned maybe a bit better performance from more cover.
The only way to get a larger cover would be to have one cast. Nothing I know of with more diffuser will take a wheel that small. I'm having a hybrid cover cast that will take the best features of the old t04s04 and old Holset and combine them. The cover will take wheels down to 58mm inducer and also wheels with very large exducers. Pretty much maximum potential for anything with t4 foot. I doubt changes to the hot side would have mattered much with the 62. The engine needs to be built around a given turbo to extract the most out of it. 10:1 CR and more favorable valve events would open up the possibilities a lot. I would expect bigger gains from the t4 tang set up if the turbo was operated at lowered flows where it wasn't close to being out of wheel. Besides I haven't seen anyone in this community come close to maximizing the potential of that wheel. There's at least another .2-.3 more than I've gotten out of it myself. Like I already mentioned getting that .2-.3 isn't going to happen by dong what everyone else already has. If you look around you can a find some really good numbers out of higher rpm 4 cylinder engines running a 62 turbo. It's been 8's tmk in an evo. I don't know the details of the combos but Id bet it's upwards of 80lbs/min and in 2900-3000lb car. Id also bet it's got higher CR and a better valvetrain than guys that are 2 seconds slower with the same turbo in the same community. Most are looking to go as fast as possible not trying to go as fast as possible with a 62 compressor. I could have switched to a 67MFS and picked up a boat load of power with boost in the mid 30's on any of the engines I ran a 62 on with little down side other than a slightly higher stall requirement and more expense. By a boat load I mean like 100+hp
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turbo96max
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- Jun 6, 2007
Bison,
Any update on the custom "hybrid cover cast" to use with say a 6266 , assuming this was like an H cover?
Nothing cost effective at this point. I've done a few one offs with 62-67mm compressors. There was no gain till over 70lbs/min. With a 62mm inducer reducing pressure drop through the intercooler 2-3psi will net more than the cover since it's not good for much more than 70lbs/min in most applications. 75lbs/min possibly with everything just right. The 64 inducer unit definitely could use more diffuser since it can move 80lbs/min. Most won't even come close to that though
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