[BruceWilkie]

The turbine needs pressure and velocity. IIRC butlers 3000+ hp twin turbo 482 uses 2" primaries and merge to 2.5" at/near each turbo. Keep in mind methanol creates @ 14% more exhaust volume over gasoline. 3000 hp is ALOT of exhaust volume.

I think "too small" primary pipe would be if primary id/csa was less than minimum csa in the exhaust port. Heavier wall helps hold heat, thus exhaust doesnt shrink as much and lose pressure to contraction. Too big hurts spool and doesnt seem to add power.

Also keep in mind tuned length theory goes out the window when a turbo is on the end of the pipe. The turbine kills reflected wave.

[455-4+1]

Thanks for the advise

Looking at Turbos sourced locally (far to expensive to ship from the USA with freight etc for one offs) the Garrets are proving a bit tricky and $$$. Turbonetics are available here and there but not many options.

I know you get what you pay for but there is a local supplier with good stocks of "Master Power" turbos (Borghetti Turbo systems Brazil ??) Apparently they started in 1974 and are OEM manufacturers for KIA among others.

Here is a link to ones available here in NZ

http://www.frantik.co.nz/MasterPower-Turbos.html

They have CNC billet compressor wheels, Water cooled 360 thrust journals.

Main thing is they are ALLOT cheaper than anything else here. I was looking at their MP-R59 compressor range which retails for $1150 NZD, there are allot of turbine choices with a wide range of A/R to choose from (advise here greatly appreciated)

They say its comparable to a GT3582 which might be a stretch but the GT3582 here in NZ is $2386 (more than double the price). Seems like the Masterpower HP ratings are a bit low for the compressor size (inefficient ??)

Just wondering if I could get away with 2 of these for under the price of 1 Garrett here ??

And if so what one (possibly the MP-R54) but it looks a little small on the compressor map. ??

[455-4+1]

Have done a bit of research and a lot of people over here running them successfully. Some ricer guys are running them into the 6's at over 200mph over here.

I think a few got a bad rap with EBay knockoffs but the genuine ones from dealers seem to go well for the money ?. Just need to choose a pair and waste gates which is a bit beyond my knowledge.

[BruceWilkie]

Originally Posted by 455-4+1

Have done a bit of research and a lot of people over here running them successfully. Some ricer guys are running them into the 6's at over 200mph over here.

I think a few got a bad rap with EBay knockoffs but the genuine ones from dealers seem to go well for the money ?. Just need to choose a pair and waste gates which is a bit beyond my knowledge.

See post 20. Taff2 is running a pair of T70 Master Power turbos... he's 421 ci vs you but these should still work well on a 455 based combo.

Looked at the link and the R6777 or R7277 both have a very wide map which is useful when limiting boost to lower levels. A pair of these could work out nice especially with twin scroll option. Couple with tight AR and big gates could make for a very responsive package.

[455-4+1]

Sorry didn't see that on post 20, thanks

Looking at the maps I am leaning towards the MP-R6777. The turbine options are 1.05 / 1.22 split (I assume the split is twin scroll right ?).You mention tight AR but the two options available are 1.05 and 1.22 split.

What would be the advantage of a split with a single 2.5" log collector running to it ?

Something like the MP-R656 has 64/74 76 trim 11 blade turbine and in T4 has .68 / .81 / 0.96 and 1.00 ?. Not sure on the total range but which out of these would be considered "tight", obviously lower number is a smaller / tighter throat, just not sure what the typical range for "tight" is.

Cheers and thanks

[455-4+1]

Just checked with the supplier, the 1.05 is a V band so would prefer that over the 6 bolt on the 1.22 I guess ??

[taff2]

Mine are .96 a/r turbine housings, with 1 5/8" headers they spool at around 2800-3000 rpm on a 421. Lots of info on these MP turbos on the turboforum.

[455-4+1]

Cool thanks for that, so I should be pretty good with the 1.05 on a 455 with the extra stroke.
Should help get off the line a bit as well and have weight transferred prior to boost coming on.

[BruceWilkie]

Split scroll will still divide ex pressure across the turbine but 2 small pipes coluld improve velocity. A cheap way would be to add 2nd outlet on a factory manifold then reduce them to 1.75" thick wall tubes (@1.5" id pipe is fine) to each turbo. (each side) Factory logs way sturdier than headers and even single 2.25 outlet to each turbo is plenty capable of supporting 1000+ hp.

Split scroll generally spools quicker/more efficient at low speed and it appears with these the bigger ar helps keep them from choking at higher rpm/boost. If dealer cant answer your question go on yellow bullet and find out if anyone has used a similar size turbo/CI combo.

btw AR # is only relevant to a given turbine and housing. An 80 mm wheel with 1.45AR could give same drive pressure as an 83 mm wheel with 1.10 AR.

Twin scroll has two nozzles across the wheel vs one, therefore may not need to be as tight.