Gday list,
I picked up my A series turbo setup today. It's a suck through setup with an IHI RB6 turbo (off a 2Litre mitsubishi Galant). The setup consists of a factory A15 exhaust manifold thats had a
turbo flange welded onto it, and the standard exhuast flange is welded shut. The inlet manifold has been made from scratch and looks like it should flow evenly, theres a 'U' shaped pipe that
connects the turbo to the inlet manifold. Theres a 1.5 inch English SU which mounts onto the front of the turbo. That probably wont make much sense until I upload some pictures of it. I
havent recieved the dump pipe yet, it was sent to me seperately. Can anyone recommend what size exhaust to run this setup on? I'm guessing either 2.25 - 2.5 inch ought to do it? What do you
reckon davo ?
I also want to get an exhaust sensor mounted (maybe in or near the dump pipe) so I can run one of those richlean LEDs.

thanks,
James.

Good to hear James. That should give u a bit of get up and go!! The exhaust i would do a 2.5 mandrel bent system. I think 3" would be too large and would lack back pressure. Well 2.5"
mandrel is what im going to put on my 1200 and its only NA so it should be ok with the turbo. 2.25 i feel would be too small for sure. We can weld in a sensor nut on the dump pipe for u if
u need one aswell. Cant wait to give u a run in my 1200 :) It should interesting!! cya

Scott
Davo

>We can weld in a sensor nut on the dump pipe for >u if u need one aswell. Cant wait to give u a >run in my 1200 :) It should interesting!! cya

Yeah, I'd love to get my turbo engine up to the sort of HP figures you've got.. I've got a definate weight advantage though, the 1000 coupe is only 660 kilos. What was
Andrew's best quarter mile time with your engine?

By the way, Is anyone else on the list going to the nissandatsun National show in Sheparton, On Easter long weekend? should be a big one!

James.

Scott/James, I thouhgt the least back pressure in a turbo the better. eg none perfect. So the bigger the better but I would suggest 3" to be a waste of money and would go with the
2.5" mandrel also. If 3" normal bent was cheaper it would probably be the way to go.
I have seen many of those articles on the air/fule ratio meters but can't remember what sensors they use to trigger the system. If they use the oxygen sensors from factory cars as I
suspect, then I'm sure I read they don't last when exposed to leaded (super) fuel. What are you going to run in the car.
With a direct path from the turbo to inlet does that mean you are not using any form of cooling of the inlet charge.

>I have seen many of those articles on the >air/fule ratio meters but can't remember what >sensors they use to trigger the system. If they >use the oxygen sensors from factory cars as
I >suspect, then I'm sure I read they don't last >when exposed to leaded (super) fuel. What are >you going to run in the car.

Leaded Fuel is no longer available here in NSW, but I plan to use optimax and PULP anyway. I've got a jaycar LED kit which plugs into the Lambda (exhaust)sensor from most factory efi
cars, I've got a few sensors too, easily pocketed at the pick'n'pull wreckers.

>With a direct path from the turbo to inlet does >that mean you are not using any form of cooling >of the inlet charge.

Yep, no form of cooling, its the worst thing about suck-through setups. So I'll have to strictly limit how much boost I will use. I would like to try setup some sort of water spray
that is activated by a pressure switch.

james.

It still depends on how much HP the engine is making and the size of the turbo. If i had an A15 turbo producing say, 150hp, 2.5" mandrel would flow the hp easy. 3" would flow the HP just as
easy therefore no real point. But if i had an A15 turbo producing 300hp (dreaming) a 2.5" system just couldnt cope. But, if i had a 3L V6 Turbo that only produced 150hp, a 2.5" would be
fine. 3" is only really nessesary in big HP engines so that it can flow the HP. When we did Croydon Autosports Civic drag car, its engines has over 1000hp and 4" pipe was needed to flow the
HP.

Then again, if i had an A15 turbo with 160hp and no dumppipe, just straight from the turbo, would the engine run more efficient than with a 2.5" system? I dont really know. I've never really
looked into it before. I supose your right because no pipe could flow alot of HP! Im assuming turbos need a little bit of back pressure tho. I mean, if Croydon Auto wanted the best out of
there drag car, would they have had no pipes right? Im stumped. Theres probably alot of room for discusion on this subject cause im not 100% sure. Im pretty sure 3" is just way too big for
an A15 turbo tho.

Scott
Davo

James, Andrew ran a few low 14 sec passes at a steet drag strip. If i took it to Eastern Creek with it all setup 100% with no problems, i think high
13's are within reach.

What sort of HP are u chasing? Are u going to go the whole hog on the head and block or are u going to use a rebuilt A14 or 15? Gotta go.....cya

Scott
Davo

I was in agreeance with you on the 2.5" but more from the point of view of cost verses gain. Then again I guess that means I mean teh cost would not net the gain. I'm like you I'm unsure but
you are right why don't the drag cars just have a large dump pipe to just get the exhaust away from the body. Mind you there is a Kiwi turbo Toyota Starlet in the latest Fast Fours and it
has a dump pipe straight out the side of the front spoiler. I guess when you read all the talk about bigger is better it most often in context of late model high horsepower cars.
I just thought maybe 3" normal pipe may be cheaper than 2.5" mandrel bent and would give similar overall flow depending on the number of crushed bends in the system. I have never had a
mandrel system made up you may be able to set me straight on the cost issue.
Gavin

The more backpressure that the turbo has, the less rpm's the turbo will turn. Back pressure is for non turboed motors, with the turbo, you want no backpressure. For street
driving, the 2.5 exhaust should be fine but If I was going to be in full competition, I would want the 3" pipes on the turbo.

>What sort of HP are u chasing? Are u going to go >the whole hog on the head and block or are u >going to use a rebuilt A14 or 15? Gotta >go.....cya

I'm not sure how much power i'll get, I just want the coupe to be pretty quick, however I don't want to have a sluggish low compression motor. So not less than 8.5:1 compression,
and around 7-11psi boost.
I'm tossing up whether I can afford forged pistons or not, they may save me money in the long run. On the head, I'll get some minor porting, maybe bigger valves if I can afford it.
And heavier than standard valve springs too. Electronic ignition is a must, standard cam, lightened flywheel and a good clutch. I want to use an A15, more displacement the better I
reckon.

Still want to sell me that 5 speed Davo? :)

James.