Modded Mustang Forums banner

Compound Boosting

8K views 29 replies 11 participants last post by  M.P. Cobra Fan 
#1 ·
#2 ·
its a pretty cool idea, but that engine wasnt stock it had upgraded pistons, and headwork, i know the builder that did it.

i still wouldnt compound boost a motor, i thought about it, but i think a TT only setup, with no blower will make more power with a lower manifold pressure that 44PSI.

that motor didnt last very long either, it lifted a head fairly quickly, and it had upgraded head gaskets, and ARP studs.

44PSI is WAY WAY WAY too much.
 
#3 ·
I wouldn't even consider pushing 44psi.. but i'd love to compound boost... as 44psi there's almost no margin for error in tuning and like you said, theres always that problem of lifting the heads...or lowing the head gasket...providing the internals can handle the pressure...
 
#4 ·
its also not easy to tune, compound boost.

best thing to do is just do TT is you want lots of power, dont throw 2 power adders into the mix unless your counting both turbo's.
 
#5 · (Edited)
Just to keep it simple..if i were looking for simplicity i'd go single turbo....:)

But compound boosting is pretty much out of most people's budget to be any kind of logical modifation. And theres no such thing as "simple" in compund. I'd try it if i could afford it and had the spare car or motor though. Not trying to kill the one i've got... Just wanna do it for fun and experience..
 
#8 ·
I dont get this "compound boosting idea" its not really compounding anything at that power level, the turbos are out flowing that so bad its not even funy, thats why they had run 44 psi to get that number. The turbos alone will make much more power, the only time the eaton would be able to "compound" anything would be when the turbos were not outflowing the eaton (like 1500 rpm). They are trying to make this out to be some kind of boost multiplyer, but really its just the turbos being pushed to an extreme to compensate for the obstruction of the eaton
 
#9 ·
compounding boost actually works pretty well. i think 19PSI on the turbo's, and 8PSI on the eaton made the 44PSI manifold pressure.

plus you have the low end power, and torque of the eaton which is also going to help the turbo's spool sooner, and you have the top end of the turbo's.
 
#10 ·
I dont see where they have 19psi on the turbos and then 8 on the eaton, those turbos at full boost by 3k anyway and start making boost before that, the question here is about cfms... one flows more than the other, that = a restriction, I read there sites info pages, looks like they just upped the boost on the turbos to compensate for the obstruction of the eaton... At 44psi they should be making alot more than 11-1200rwhp
 
#11 ·
im almost positive they were running 19 turbo's/8 eaton to get 44PSI manifold PSI. i was talking to John Urist (owner of hellion) over the phone about it.
 
#12 ·
the builder that did it was the turbo company itself testing the kit to adapt to the stock terminator motors, and the motor in the MMFF article if thats the one that the link goes to was a stock motor with a different midpipe and catback
 
#16 ·
1200 hp on the stock engine did sound like a strecth...:)

MLS head gaskets and ARP head studs too im asuming?
i know it had aftermarket gaskets, dunno what brand, and yes headstuds too.
 
#17 · (Edited)
compound boost

i had to sign on this to post my opinion on the totally wrong accusations about twin charging ! first of all it been around for more than 60 years they used the wonderful idea on a fighter plane to give it more power to get off the acc. you will see VW do this on new car they have . you see it old drag rails as a turbo into a turbo which is still compound boost and fords new diesel ! compound boost! and as for the head lifting it was stock!!! it was not aftermarket. i talk to them alot about my set up. it was a new mustag the white one w blue racing stripes they ran 35psi befor it lifted the stock heads and tty bolts. beside there are mod motors taking 30 and 40 psi all day long! with out head studs and and ss gaskets no! without ss top ring no! you motor will not last but with headstuds, ss piston rings ,ss head gaskets, and( if your not a cobra with good rods )youll need rods 1000 hp rods are good and a forged crank then yes with theses parts mod motors are bad to the bone and will handle alot of power due to the fact the crank is so far into the block unlike older v8 and chevys. twincharging is only hard if you make it hard it helps if you already have a sc like a cobra or gt500 and they where not running 19 psi on the turbo more like 12 and 7 you dont need to run much boost on the turbo there is a equation for it. and if you have ever drove ethier of the two set ups you will know!!! that if your running 44psi!!! with two turbos its a f**** dog off the line with out 4000 stall!! and a sc on the street and track will run out on the big end on most stangs w/ stock sc and twin charge set up will turn it into a monster!! and the!!!! sc is not !!!!! a restriction only if you dont do your math which there is an equation for finding how much turbo you need and you put two giant turbos on it and one turno will not make more power than two sized right if you ever watch a car at the drags with 1 giant turbo stage alot of times the car is still spooling even after the light turns green
 
#21 ·
It's not like they were putting 44lbs from the turbos into it. Did you go for a ride?

Yeah compound turbos on a diesel are fun. On my buddies truck it still took a manifold pressure of over 80psi to make over 1,000 hp on air/fuel. Who knows what the drive pressure was, I'm sure something high. Two different things for sure.
 
#25 ·
The old air plane argument is for internet techs. First, a car is not a plane... there are all kinds of air density parameters that play into it. Second, those engines and fuel are not the same as today. Third and most importantly the reason for the turbos was not power, the reason was efficiency and reliability. They used the turbo to dissipate heat. You can watch hellions own video labeled 1000hp GT 500 - they removed the supercharger at the end and made more power with a better powerband - in fact thats how they made the 1000 hp - their advertisements are soo misleading and shady, I wouldn't trust them at all. Its a shame they do this, because it seems to me that their kits are top notch quality... but way over priced.
 
#26 ·
im doing the hellion twin 57s down the road with the stock eaton, possibly ported. i want like 700ish, its a sick setup you cant even see the two turbos. im just not going to tell anyone locally when i get it done.
 
#29 · (Edited)
Lol, but anyone with any considerable car knowledge will know it when they hear it.:)


And like he said, the s/c isn't so much of an air restriction as it is a drag and heat restriction. You're pumping boosted air into a compressor so it's essentially making the s/c more efficient. But at the same time, the air is being heated as it is compressed. The S/C has an intercooler, but intercoolers are also restrictions. You have a supercharger eating power from the belt, two intercoolers, and two producers of heat. Ultimately, this setup will be less efficient up top in the powerband than just the turbos alone, but it'll make more low rpm torque because of the acceleration of the air (the rapid increase in boost pressure at low rpm).
 
#27 ·
ok can anyone tell me why the supercharger would be a "restriction"? because to me if the supercharger is a restriction then a valve should be opening and just allowing the air to flow right through....think theres a word for that. pretty sure its called a blow by valve (not 100% sure on that) now if this system doesnt have one of those then its kind of pointless/retarded, however if it does contain one of these then i could see the advantages of it over a super, turbo, or even a twin turbo.
 
#28 ·
supercharger takes a percentage from the belts much like your a/c does, as where a turbo does not because it runs off of the exhaust that you have no use for, although lag is the downside where as with a roots/twinscrew there is little to no lag.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top