Project CA20DETT

[pnblight]

yeah not a bad idea but i don't think the interfance fit would be enough as there is quiet a bit of load on the pulley. But if i did this i could then drill a hole on the seem of the to halfs and dow it. Removes any posible of slipping. might be my best plan for now will try and see if i can get a blank pulley tho.

pete

[float_6969]

IDK, I've seen interference fit items take some pretty amazing loads. But as you said, a simple dowel would eliminate any chance of slipping.

[Bwana]

ive been planning to use a single t3 flanged tubrbo\ (after dynoing with an sr t25 ) on the ca20

but the only/best single way i can see a TT setup working on a small engine like this is 2 different sized turbos.

a big one right on the manifold like normal, screamer pipe or not. then the larger exhaust flow pipe going back to a rear mounted small turbo(even the stock CA t25)

that way the big turbo will be the pirimary concern, and all its exhaust wil travel together, and the wastegated exhaust wont matter, it will be plenty to drive the smaller turbo

the trick would be to have the chargepipe from the rear turbo join right after the intercooler from the big turbo (the long distance under the car acts like an intercooler...thats the theory for rear ounted turbos anyway)

you could run both turbos well inside their efficiency range

and the small turbo will start producing boost at what? 2500? then that will only help spool the bigger turbo faster.... you could even go with a turbo thats not efficient for a 2 liter... as the small turbo running ~10 PSI will bump it up to a little over 3 liters

unless you want to try and do twin uber-small turbos, each running off 2 cylinders ?

but yeah, its just f'in cool

Slightly off topic, but what you've described is exactly opposite to the proper way to install compound turbos. Basically you mount the smaller turbo on the manifold, pipe all exhaust from it (it's internallys wastegated, and the wastgate dump goes back into the same pipe) to the big turbo and from there out the pipe. The intake goes to the big turbo first, from the boost outlet on the big turbo to the inlet of the small turbo, and from the outlet of the small turbo to the intercooler. The max system pressure is tuned using the wastegate on the big turbo, the balance is tuned using the wastegate on the small turbo. If you want I can get some pics of my brother's truck ('00 Dodge Cummins) which we've tt'd. It makes over 75 lbs by the way...

[sideways danny]

what's wrong with good old-fashioned welding?

[float_6969]

I had considered that but the pully is so thick that to get good, deep penetration, you'd have to get it pretty hot, and it's such a small peice of metal I didn't know if it would keep it's integrity.

I guess now that I think about it, you wouldn't really HAVE to have COMPLETE penetration. You could weld it on both sides and if you only got 25% depth penetration on each weld, you'd still have 50% of the metal welded together, which would probably be enough.

[Bwana]

If you bevel the weld joint properly and weld it on a cold table you should be ok.

[float_6969]

I still don't think you'd get 100% penetration, but as I said before, I think it would be strong enough with out it.

[pnblight]

yes all great ideas but i think a combination of both BUT when you fit the two pieces together you drill a hole on the seem and dow it before you weld. Which will lock the two together and there is no chance of them slipping.

pete

[tyrannix]

maybe im all funked up, but welding wouldnt even be necessary.

just a spacer (like the inside of teh CA20 cog) and another 'woodruf key' (thats what its called, right? ) to keep the interferance fit, then the whole expand and shrink fit thing (the guy who did my tooth wheel onto the crank pulley did that, that bastids not going anywhere)

CJ

[float_6969]

That's what I just described earlier...

[pnblight]

the size difference between the two i don't believe is big enought to accomodate a second key

[float_6969]

I don't think it is either. That's why you'd have to get some sort of spacer and a bigger key.

[Swedish Mike]

A 4-cyl Twinturbo, crazy but cool. Dual TD04-16T´s and 538whp.

Testing, testing, you can see a piece of the second turbo down low.

In car and finished.

Dyno sheet.
Modified by Swedish Mike at 2:08 PM 1/8/2007

[pnblight]

nice picStrange to see a intercooler system place where it, as i was look at the silvia last night and wanted to reduce the large volume of cooler piping(and thus lag) and came up with the idea to place my gtr intcooler in the same position as shown here (i haven't seen it done before) bit freeky. I think it a great idea tho as the CA18 has a **** load of space in front of it and if you get the intercooler back in the car less chance of damage due to Drifting offs.

Peteps if this is a twin (cant see both turbos) i like the traditional power curve you get from a twin turbo likw this one which is quiet linear and has its most rapid acceration at the start of the run and then tapers back slowly.

[Swedish Mike]

It´s a twin turbo. Don´t know why but he wanted to test it.

That´s why I use the Volvo water coolers in S13, you can mount an IC just like the pic and use short pipes. Easy to fit as well. .

Lower turbo.

[pnblight]

i thought the results would have been reason enough no? did it not perform to expectations? May i ask what boost the engine ran as its a rather unusual boost curve.pete

[datsunboy]

check out the crazy timing belt

[Swedish Mike]

i thought the results would have been reason enough no? did it not perform to expectations? May i ask what boost the engine ran as its a rather unusual boost curve.pete

True, but I would lie if I said you need a twin turbo to make that power.Would be interesting to see the same engine but with single turbo and compare dyno sheet´s.He ran 1.8 bar, close to 30 psi if I remember math class.

For further info, it´s a 2.3 litre Volvo 740 GLT engine, 16 valve B234F.

[pnblight]

True I do believe you could gain very similar out right hp with a single BUT from my experience you will have a much different power curve (low and mid range suffer).

The twin (multi) turbo system tend to give a nice smooth arc proud of a linear line in the mid range (trying to remember the correct term) with the steepest part on initial acceleration.

The single turbo system tho it might reach similar final (top end) hp will have a much different power curve in low and mid range rpm, on initial acceleration it will have a slower acceleration than the turbo for the first section but as it reaches mid range will then develop the (light switch effect) power build very rapidly and Plato off. This looks more like a sign wave dipping under the linear line at first and only rising above the linear line in the top end.

What this means is the twin(multi) turbos are the pic of the crop for circuit and street use as they deliver smooth predicable right through the rev range with great spool up or recovery response .That’s why the best top end street cars produced by manufactures when this way i.e. Nissan GTR, Biagatti w16 quad turbo, Porsche, BMW and in racing F1 they ran twin turbos on 1500cc motors (how people forget) if there was no racing advantage to running twins on F1 car there is no way in hell they would have done it. We owe most of our now advanced turbo and fuels to the F1 turbo era. The Single normally finds it home in motor sport not requiring such razor response Drag Racing, Dyno Comps where once in to the power band it relatively easy to keep it there. The other advantages of a single setup in it much simpler and less parts and from original manufacture much cheap to build that’s why your more mid range priced cars are built this way to save costs.

Pete

[Swedish Mike]

True I do believe you could gain very similar out right hp with a single BUT from my experience you will have a much different power curve (low and mid range suffer).

The twin (multi) turbo system tend to give a nice smooth arc proud of a linear line in the mid range (trying to remember the correct term) with the steepest part on initial acceleration.

The single turbo system tho it might reach similar final (top end) hp will have a much different power curve in low and mid range rpm, on initial acceleration it will have a slower acceleration than the turbo for the first section but as it reaches mid range will then develop the (light switch effect) power build very rapidly and Plato off. This looks more like a sign wave dipping under the linear line at first and only rising above the linear line in the top end.

What this means is the twin(multi) turbos are the pic of the crop for circuit and street use as they deliver smooth predicable right through the rev range with great spool up or recovery response .That’s why the best top end street cars produced by manufactures when this way i.e. Nissan GTR, Biagatti w16 quad turbo, Porsche, BMW and in racing F1 they ran twin turbos on 1500cc motors (how people forget) if there was no racing advantage to running twins on F1 car there is no way in hell they would have done it. We owe most of our now advanced turbo and fuels to the F1 turbo era. The Single normally finds it home in motor sport not requiring such razor response Drag Racing, Dyno Comps where once in to the power band it relatively easy to keep it there. The other advantages of a single setup in it much simpler and less parts and from original manufacture much cheap to build that’s why your more mid range priced cars are built this way to save costs.

Pete

Yeah, normally like that but this car got two turbo´s made for 2.3 litres each, might be a bit laggy.Either way, it´s cool to run TT in a 4-cyl.

[r34 gtr]

that setup is pretty sick. its a pretty big engine though, so a twin turbo setup is a little more feasable. it just wouldnt be worth it on a 1.8l like ours, at least for the applications most of us will use our cars for. i think my peaky single turbo powerband is kinda fun. i find a linear powerband kind of boring, haha.

on a side note, wouldnt you be able to flow twice the volume of air at the same pressure as a single turbo? correct me if im wrong

[Swedish Mike]

that setup is pretty sick. its a pretty big engine though, so a twin turbo setup is a little more feasable. it just wouldnt be worth it on a 1.8l like ours, at least for the applications most of us will use our cars for. i think my peaky single turbo powerband is kinda fun. i find a linear powerband kind of boring, haha.

on a side note, wouldnt you be able to flow twice the volume of air at the same pressure as a single turbo? correct me if im wrong

Jupp, but you will have to split the exhaust flow as well. Only 1.15 litres cylinder volume per turbo.

[pnblight]

no the turbos aren't the thing that governs the air flow, the motor(head intake system and exhaust housing of turbine(plus exhaust govern the air flow at pressure.

Try and think of it this way ( for this example we will use a constant which a motor is not) the motor is a piece of pipe with a restrictor in it, and know you are trying to flow air through this pipe, it will flow air happly until it starts to build back pressure which is pressure in the pipe (boost) and as you increase the presure in the pipe the air flow will increase but in a ever decreasing amount compared to the increase of pressure(due to increasing losses of fraction and heat). So this effect will happen no matter weather your use one pump or two, three or four.

The reseason the twin turbos sytem spool quicker and develop power earlier in the rev range is mainly due the fact of pulse clarity (basically it was discovered in the 1930's and again in the 1960's that the clearer the exhaust pules signal the quicker the turbo will spool i.e. 4 cylinder 2 litre will spool better than 6 cylinder 2 litre and this is also the reseason the nissan std manifolds have the split exhaust housing (when you look in the std exhaust manifold where the turbo bolts on you will see a separation plate. New single turbos have been try to get around this with split exhaust housing (you might have seen a few around)

pete

[float_6969]

Wouldn't this also help to reduce reversion since one cylnder would be at in it's compression stroke and the other on it's exhaust stroke? Since the pulses are 360° apart, and aren't mated with the other 2 cylnders, I would think that it would really help to keep the combustion clear of exhaust gases.

[iliketocrash]

on a side note.. there are a couple of videos of this car in action and the car is ****ing sick. i can't even explain how awesome it is to see the car in action. if i find 'em i'll post 'em.