Im helping tune a 12a turbo. I play with my fd on a regular basis but i am unfamiliar with the 12a's limitations etc.

The engine has high compression rotors but high milage. We have not compression tested it yet but with the leading plugs out it sounds good.

It is running a t3 turbo currently @ 6 psi. (elford turbo) For those unfamiliar it has a SU carb passing fuel through the compressor with no intercooler.

It has a 12a turbo dizzy

direct fire ignition mod

Fuel system consists of a holley blue top fuel pump and reg.

Also has water injection (pre turbo)

This is the basic spec. We only have racing beats ideas for the timing.

so basically im looking for ideas on afr targets between 5 and 14 psi and timing targets if poss.

Thanks Scott

 

well the 12a turbo dizzy retards boost up to 5 psi, so if you more that 5 pounds of boost , especially with 9.4 compression and pump gas i would highly reccomend locking the centrifical advance weights in the dizzy. also set the timing at no more than 10 degrees advanced total for the safety of your motor.. use the 9 heat range spark plugs and look for the afr's on the 11's to be again on the safe side.. with conservitive timing and a fairly rich air-fuel mixture 10 pounds of boost should be very reliable!

i sent your buddy a pm as well

 

Thanks. I just spoke to him.

He had been told to lean the fuel off to 12.5 afr with water injection. I personaly think this is a bit lean with no intercooler.

Scott

 

thats definatly too lean, even with an intercooler.. rotarys make more power when you run the afr's in the 11's anyways(forced induction that is)
the water injection has nothing to do with how rich or lean you run the car, it simply fends off chance of detonation, usally allowing a person to run more boost safely...
i would love to see pics of the setup , i have alot of expirience with the su carburators from my first 5 cars i owned,, all 60's era volvo's, p1800 and 122 models to be exact

 

i will get him to send you some pics of the set up.

He has put marvel oil in the carb to get a quicker response but he is telling me that the car was running around 12,s today. I will need to go log it with him. I just hop his jet will supply that amount of fuel.

11 afr always seems to pull so much better. Its just a case of getting to know the limitations of his motor without over stressing it. Since the turbo kit has been fitted the only time it has got close to 11 afr is on idle LOL

Scott

 

I would like to see the pics posted. what size is the su carb? we were using 1.75 ones on bug engines a while back.

 

was this blow thru or draw thru?

 

Its a draw tho carb. i will chase him for some pics. I dont know the size of the carb.

 

its probably a 1 3/4" su.. the big ones off the old jag e types are 2" but cost$$$$$

 

Providing the neddle jets he has will fuel it then i was thinking he may as well turn the boost up a little. The turbo must be below its efficency range plus he would like to get near 200 whp so he can play with the FC's and the least gifted fd drivers on the strip. LOL

Scott

 

thats fine but dont forget about the timing.. enven if you have enough fuel, you can still pop the motor with too much timing!!!

 

Cheers. Im hounding him about the timing all the time. I will try and get some pics up tomorrow.

Scott

 

ok just got the camera out appologies for the focus....

 

and again..

 

ok and some info to go with...

it uses a Garrett AI research T3 turbo charger with a 1 3/4 inch SU HIF 44/1 CARB
the turbo as stock runs 6 psi
elford suggest retarding the ignition by 1.25 degree every 1000 rpm
not recommended to run above 7k

this all taken from the elford publications from back in the day as well as mag reviews.

ok that was then this is now, i have a straight through exhaust full compliment of gauges, A.F.R, knock, water temp etc and am looking as having the car to run on the strip and not day to day. the interior is stripped from back to the front seats.

im running holley blue pump and reg, cooling mist water/alc injection
second gen ignition mod, 12A turbo dizzy, front mount oil cooler, locked diff.

running the car on optimax 98RON with a little additional premix to suppliment O.M.P

cheers Ollie

 

ok just used the wideband,

its pulling in the 11's afr on boost and leans out slightly towards the high end at 7k around 11.8

this was in 2nd and 3rd at 6psi with no water/alc injection.

the idle is at 10-10.5 afr and im using the needle/jet which is one step richer than the stock jet.

i have the timing set at stock with the 12a turbo dizzy which gives around 5deg boost retard.

im gonna try to set up car at stock (6psi) boost and then hopefully raising the boost to around 10psi if there is nothing stopping me,

does any one have any tips/hints about what is the best way to do this is?

i was gonna remove 1 degree total timing per 1 psi of boost i add.

im gonna wind out the wastegate real slow as i dont have a boost controller.

any input/thougts greatly appreciated!

Ollie

 

You should have less problems if you're running alcohol injection. You may have to pull a lot of fuel if you're doing alcohol injection, too, but it depends on how much alcohol you're injecting and what AFR's you're looking for.

 

The prob he has with alch injection is that he has to go pre turbo with it. When it flows it slows and stalls the compressor

Scott

 

AFAIK, the best place for alcohol inejction is right at the start of the intake manifold, usually right at the end of the intercooler (on cars with TB's).

Why does he have to go pre-turbo with it?

try decreasing the flow rate. If you can't adjust the rates and such to get good performance from the alcohol injection without stalling hte compressor, you may want to look into it more. If you're running a lot of boost, you may be heating the alcohol/fuel mix enough that you're combusting it in or right after the turbo, in which case you will stall out the turbo due to not enough exhaust gas expansion to keep the turbo spooled. If it's only like 4-5 psi of boost, it probably is something else.

 

at the moment the water/alc is pre turbo, on the pics you might be able to see the black hose going into the air filter,

i dont have an intercooler but it is a huge job to remove the inletmanifold as i have to remove the carb, exhaust, turbo and then the manifold to drill the nozzle.

it is possible to do but very time consuming, would you say it was a worthwhile job?

with the methanol what quantity or AFR works best?

Cheers Ollie

 

With the stock WG actuator i did not get much higher boost as 8PSI.
It's a small turbo and i doubt if it's flow enough for higher boost / RWHP

I got 221 HP out of it, @7 PSI but i did have do a lot to get it there.
(direct fire, good timing, 3" full open exhaust system, reroute the turbo oilfeed pickupline, electrical cooling fan, 2 stock oilcoolers, custom cold air intake, customer radiator, and a whole lot of polishing/porting in the carb and manifolds)

But the faces of people in TII's and stock FD's when my 27 year old bitch plays with them..... is like the VisaMastercard add..... PRICELESS.....

Greetings
Mireck

 

I would also like to add that he has no egt gauge so timing is gonna be on a trust basis really ( ie who you trust ).

I would say from my fd that 11.8 afr at high end is ok at 7 psi of boost but im not experianced in the 12a or 12a turbo. I think he can determine where peak tq is from his knock sensor and the wide band. With the needle jet that he is running it seems from what he says that it gradually leans out over the rev range. With that in mind as long as his afr is good a peak tq then the fact the jet leans out a tad after this point should be irrelevent as long as it stays in the high 11's ?

I was thinking that if the jet is placed inthe inlet manifold due to the short runners, he should go high percentage methanol say 70:30 or even 100% to limit the amount of water ingested in to the engine ?

Really i suppose if he pulls the inlet manifold then he should add a thermocouple in for a AIT gauge. This could really transform the water injection tuning.

Scott

 

very true!

 

What port etc did you run ?.

im interested in the power gains and the power to weight gains from the fb. You can pm me or mail me if you want sdminus@yahoo.co.uk

Scott

 

ok just back from a go at tuning.

ok was running 14psi with 0.75gph of water/methanol (50/50) pre turbo.

retarded the timing by 2 degrees, switched to bur9eqp plugs and installed an exhaust.

was seeing around 0.80 L on the wide band and she went hella fast.

were do i go next?

i was gonna try a bigger jet in the water injection but no more boost.

and do i need to go any richer?

Cheers

Ollie