73 replies to this topic

[mini13]

go and look at some compressor maps, do the math and come to the right conclusion.

[Sam Walters]

i would love to see it done mate would be wicked to say yyou have a twin turbo mini

There is a difference between saying you have something and actually having something. Its the same difference between saying your going to do something and actually doing it.

Edited by Sam Walters, 30 September 2010 - 08:10 PM.

[mpihornet]

you dont get as big a hit (change or delta for your calculus nuts) going forced induction after multivalve/multiport as you do forcing small valves and lame combustion chambers. the old pushrod sube (vw flat 4 with siamese intake and exhaust) was a great example....... poor performance until it got the turbo then it behaved like a hot rod. the vw flat four is teh same.... its got tiny valves and very small head to valve surface area ratio, let alone port cross sectional area. 5 main bearings on a four banter help when it comes to big power. at the end of the day, how is your austin a30 inspired gearbox going to hold up? I'd go 7 port, or turbo, but frankly, the bmw k bike head is a better option, and you can inject any car, any bike, any type of engine, so that would always be the best way to go. you need to set limits (he says after destroying several turbocharged and fuel injected monsters)

[mini93]

so...with all that your saying the gearbox wont take the power then? theres quite a few powerful turbo motors kicking about now and, as long as built correctly with best components have stood upto the abuse (sure if you can afford to go 7 port turbo you can afford a dog-box with true LSD diff)

[mpihornet]

im saying i dont think there is much point having both. and at the end of the day, whats the max power a custom dog box can take reliably for any lengh of time? and whats the most power you can put on a 3 main crank? i bet you can already exceed those numbers with either so why both?

[mini13]

what exactly did you destroy?

you dont get as big a hit (change or delta for your calculus nuts) going forced induction after multivalve/multiport as you do forcing small valves and lame combustion chambers. the old pushrod sube (vw flat 4 with siamese intake and exhaust) was a great example....... poor performance until it got the turbo then it behaved like a hot rod. the vw flat four is teh same.... its got tiny valves and very small head to valve surface area ratio, let alone port cross sectional area. 5 main bearings on a four banter help when it comes to big power. at the end of the day, how is your austin a30 inspired gearbox going to hold up? I'd go 7 port, or turbo, but frankly, the bmw k bike head is a better option, and you can inject any car, any bike, any type of engine, so that would always be the best way to go. you need to set limits (he says after destroying several turbocharged and fuel injected monsters)

[Turbo Nick]

im saying i dont think there is much point having both. and at the end of the day, whats the max power a custom dog box can take reliably for any lengh of time? and whats the most power you can put on a 3 main crank? i bet you can already exceed those numbers with either so why both?

i stripped 1st gear from a normal syncro SC clubman set after 30k ish miles @ 170lb/ft, now running the same style box again but with an ATB LSD and 200lb/ft and it's been ok so far. totally bog std crank and rods for all this time aswell.

thats on a std turbo'd 5 port

[mini93]

theres quite a few people running reliably on turbo, hardly exceeding the 3 bearing crank. Also remember with the turbo set up you dont have to worry about stressing rods and crank as much, remember the a-series is relitivly long stroke standard... 150 N/A takes alot-alot and lots of things become stressed and rebuild times are reduced. 150 with forced induction isnt a massive amount, stuffs not nearly as stressed compaired to N/a can easy wind down the boost for daily and up it for cometition etc. My engine builder has suggested if i go any further with my spec i should be opting for steel internals and thats just around 100bhp but as i say i know theres a few turbo chaps with standard internals still.
Theres nothing saying he couldnt use the turbo as a little "kick" to the spec, low boost set up whilst still keeping the compression in a point where its not daft off boost
Not sure how much a (non custom) dogbox can take but swift tune/ Quaife one has stood upto alot of abuse in competition and i think jimster on Turbominis runs one, using a Turbo changer K1100 head set up, as far as iv heard over on there its stood up so far

[mini13]

you can put lots of horse power through a 3 bearing crank reliably,

why would a custom dog box be needed? plenty of people are putting over 200hp through a syncro'd straight cut box, the currently available dog boxes with their wider teeth seem to be ok for much higher figures.

im saying i dont think there is much point having both. and at the end of the day, whats the max power a custom dog box can take reliably for any lengh of time? and whats the most power you can put on a 3 main crank? i bet you can already exceed those numbers with either so why both?

in this link they a car that has been runnig the same dogbox for 3 or so years under a turbo'd bmw head, apart from the 100 (HARD) laps of pembry they mention and the other track days its done its reguarly on the dragstrip.

the biggest issue has been some munched thrust washers

http://www.turbomini...p...&tid=294969

[Wil_h]

I think that people are missing the point of the 7-port. Yes, there is potential for more power, but not massively more over a godd 5-port (especially in forced induction).

The BIG advantage is the ability to fuel inject, which has a massive advantage in a number of ways.

I would hazard a guess that the thing that kills off most turbo engines is melted pistons caused by poor fuelling, even a perfectly set up HIF will be lean in place.

I agree with a lot of the above about reliability, my 998 turbo race car has had the same crank and rods since I built it over 8 yearss ago, and it's been used a lot.

[mpihornet]

I think that people are missing the point of the 7-port. Yes, there is potential for more power, but not massively more over a godd 5-port (especially in forced induction).

The BIG advantage is the ability to fuel inject, which has a massive advantage in a number of ways.

I would hazard a guess that the thing that kills off most turbo engines is melted pistons caused by poor fuelling, even a perfectly set up HIF will be lean in place.

I agree with a lot of the above about reliability, my 998 turbo race car has had the same crank and rods since I built it over 8 yearss ago, and it's been used a lot.

thanks for backing me up. you can fuel inject twin port but its never as good. with 7 port, i think you may as well go bmw khead.

flow rates for carbs are always based on 1 atmosphere. in the states folks often put tooooo much carb on blowers because they go by the flow rate numbers, but those numbers are meaningless when going an extra atmosphere or more with forced induction. With my mustangs, we tried to go smaller carb and bigger jetting and that worked pretty well, where as going bigger carb often ended badly. Propper Injection in conjuction with turbo's or blowers is always the solution.

Edited by mpihornet, 01 October 2010 - 12:12 PM.

[mpihornet]

what exactly did you destroy?

you dont get as big a hit (change or delta for your calculus nuts) going forced induction after multivalve/multiport as you do forcing small valves and lame combustion chambers. the old pushrod sube (vw flat 4 with siamese intake and exhaust) was a great example....... poor performance until it got the turbo then it behaved like a hot rod. the vw flat four is teh same.... its got tiny valves and very small head to valve surface area ratio, let alone port cross sectional area. 5 main bearings on a four banter help when it comes to big power. at the end of the day, how is your austin a30 inspired gearbox going to hold up? I'd go 7 port, or turbo, but frankly, the bmw k bike head is a better option, and you can inject any car, any bike, any type of engine, so that would always be the best way to go. you need to set limits (he says after destroying several turbocharged and fuel injected monsters)

heads (cracked), pistons (detonation) , turbos (sheered shafts), valves , rod bearings and cranks, one or two gearbox's, a mopar rear axle etc. the victims were mustangs, gpz1100's, escorts chv's and subaru pushrod motors (and a couple of v8's).

[wolfie]

I think that people are missing the point of the 7-port. Yes, there is potential for more power, but not massively more over a godd 5-port (especially in forced induction).

The BIG advantage is the ability to fuel inject, which has a massive advantage in a number of ways.

I would hazard a guess that the thing that kills off most turbo engines is melted pistons caused by poor fuelling, even a perfectly set up HIF will be lean in place.

I agree with a lot of the above about reliability, my 998 turbo race car has had the same crank and rods since I built it over 8 yearss ago, and it's been used a lot.

thanks for backing me up. you can fuel inject twin port but its never as good. with 7 port, i think you may as well go bmw khead.

flow rates for carbs are always based on 1 atmosphere. in the states folks often put tooooo much carb on blowers because they go by the flow rate numbers, but those numbers are meaningless when going an extra atmosphere or more with forced induction. With my mustangs, we tried to go smaller carb and bigger jetting and that worked pretty well, where as going bigger carb often ended badly. Propper Injection in conjuction with turbo's or blowers is always the solution.

I dont think wil is backing you up hes not agreed with anything you have said i suggest you read both posts again, injection and charging a siemesed port head is very very difficult and very involved due to charge robbing so you clearly dont know much about it with quotes like this "you can fuel inject twin port but its never as good", And........ "you may as well go bmw khead" ignoring the fact you will have to add an ecu and plenum the expense and time for dry decking, re-drilling block, machining pockets in pistons, full fitting kit, machining cam cover expensive HG ect ec ect really outways the almost bolt on aspect of the 7 port? sorry but your talking tosh, the ONLY rason to go K head imo is for out and out power 250-300 brake and/or the 16v kudos

[mpihornet]

I think that people are missing the point of the 7-port. Yes, there is potential for more power, but not massively more over a godd 5-port (especially in forced induction).

The BIG advantage is the ability to fuel inject, which has a massive advantage in a number of ways.

I would hazard a guess that the thing that kills off most turbo engines is melted pistons caused by poor fuelling, even a perfectly set up HIF will be lean in place.

I agree with a lot of the above about reliability, my 998 turbo race car has had the same crank and rods since I built it over 8 yearss ago, and it's been used a lot.

thanks for backing me up. you can fuel inject twin port but its never as good. with 7 port, i think you may as well go bmw khead.

flow rates for carbs are always based on 1 atmosphere. in the states folks often put tooooo much carb on blowers because they go by the flow rate numbers, but those numbers are meaningless when going an extra atmosphere or more with forced induction. With my mustangs, we tried to go smaller carb and bigger jetting and that worked pretty well, where as going bigger carb often ended badly. Propper Injection in conjuction with turbo's or blowers is always the solution.

I dont think wil is backing you up hes not agreed with anything you have said i suggest you read both posts again, injection and charging a siemesed port head is very very difficult and very involved due to charge robbing so you clearly dont know much about it with quotes like this "you can fuel inject twin port but its never as good", And........ "you may as well go bmw khead" ignoring the fact you will have to add an ecu and plenum the expense and time for dry decking, re-drilling block, machining pockets in pistons, full fitting kit, machining cam cover expensive HG ect ec ect really outways the almost bolt on aspect of the 7 port? sorry but your talking tosh, the ONLY rason to go K head imo is for out and out power 250-300 brake and/or the 16v kudos

my understanding is that canems have a good tunable siamese system, i was looking into it. but im happy to admit that my experience with a series engines is much limited compared to my experience with other engines and gearboxes, and far inferior to others here. personally at the moment, im happy with mems mpi, and have no intention of racing. all i was trying to say at the begining was that you don't get as big a hit in power gain with forced induction with good flowing heads as you do with poor flowing heads, which im pretty sure i got agreement on. I do however agree that its hard to inject siamese heads and the way sube did it was to bolt injectors right into the head at the port, but then, its cross flow so there was room. thats why i was looking at the canems system. I would agree that 7 port will give you more injection options if your going forced induction or not, and ill agree that that the k head or kad head leave little room at the front for intake plenums. i guess its just for me, where do you draw the line? there is no limit to what you can spend, or time you can consume faffing, and as i said, im not racing so ive drawn my line pretty close. i did not know that the 3 main crank and mini gearbox could take so much power and for that i also stand corrected. But if i were going to spend all that cash on a 7 port and turbo, i'd strongly consider the k head. not that ill ever do either.......