Weight of turbos

[928s]

Hi gang one of the reasons I git interested in the Toyota motor was that fact it was so light and well built. I planed on having N/A engine. These are more responsive and certainly lighter. But I'm thinking they probably wont last as long and will cost a ton of money, money which I no longer have, the reasons I wont go into. I read a post where there was a 3uz putting out over 600 rwhp. This would be perfect.

My drivetrain could probably handle that, although I want to develop the power up higher to stop the low rpm torque breaking my very expensive and rare gearbox. The car is a Porsche 928 BTW. Anyway I would like to set the redline at 8500 rpm but really only use 7500 to 8000 rpm on the track, the higher rpm would be for an assault on the 928 speed record, with a porsche 928 engine it achieved 338kph or 211 mph. The cars are quite stable at these speeds.

What will I need to do first to make that 600rwhp? then what will I need to do to make those rpm figures I quoted be reliable? I dont want to lose an engine at 340 kph!

Any input welcome, what do lightweight turbos weigh, I have heard Indy car turbos are very light, also is anybody using water intercoolers? Please put me on the right track.

Cheers Greg

 

[R-Jay]

turbo system, twin or big single
good exhaust and intake
good aftermarket ECU
low comp forged pistons
forged rods
good cooling system, a2a or w2a
total valvetrain upgrade with cams
headwork

there's a general list of parts you could do with....it's the list im building mine off (though im going piggyback due to a lower goal hp) mind you, you can get away with less, but more is better.... to get those figures, you'd be spending big, so i don't think you should skimp out on parts that might be critical.

 

[Trvln Nalzmn]

For speed record I'd use a big front mount intercooler and then a water to air after that. Put coldest liquid in water to air.

 

[928s]

Hi guys when I posted last nite I was really tired and I should have added a few more details of things I know. My background is a mechanic and have friends who are engineers. I also keep upto date with some of the latest technology available, such as Race Tech and Race Engine Technology. So I understand the basics. What I really need is more of the specifics.

E.G there is forged pistons and forged pistons, what material to use 2618a or 4032. They both have different benifits, also piston design, that is ring thickness and placement. Ceramic coating of the crowns? Why do the cams need updating? Is it because of my goal with the revs? Lower lifts are normally better with high revs but the point off intake closing can be an issue also on the exhaust side it may not have enough duration and the motor may suffer pumping losses.

As far as the intercooler goes, one of my friends who works in airconditioning talked about using it to run the intercooler, the biggest name in town is Laminova, they also have options to use this. The other reason I was interested in turbo cahrging was that I didn't want too much low end torque which might break the gearbox. I believe the torque should be limited to 500 ft pounds at the wheels, if I develop the power up higher then the gearbox strain should be lessened? Am I right about that? BMW say their new 5 series M5 follows the high rev concept so that they can use lighter components in the driveline because the power is developed higher up the rev band. Having stump pulling torque at low revs seems to me atleast to have more potential to break things I reckon anyway.

Now to the question on weights of the turbos and system as such, the reason I may switch to Toyota power is its lightweight. There is nothing wrong with the Porsche power. The stroker motors powered this guy to 338 kph, he now has even more power, 550 rwhp and the torque was limited to 500 ft pounds so that the gearbox would be preserved. But the engine is heavy and expensive. Building it mself it would cost $30k to $35k. If I had a lexus motor and saved 80 to 90 kgs and had only 550hp that would be ok in N/A form, I would have to forget about the top speed but no biggy.

If I went forced induction that is when I most well go the full hog. What is that going to cost and the weights please. I dont want to add 40 kgs to the car if I can help it. Otherwise I might be back trying to go a 4.7 liter N/a path. Normally N/A is always the most expensive way to go.

Thanks for your inputs and sorry for the long post.

Greg

 

[turboandrew]

the 4.7 (2UZ) block will weigh ~50 Kg more than the 4.0 and 4.3 liter 1/3UZ motors. I would think a supercharged 1UZ would be the best bet for weight, useable power, and ease of installation (a lot less pumbing than a turbo setup).

Does anyone have an exact weight for the 1UZ? I suppose I can weigh my complete 2UZ, but I need to get a scale that will actually work in that range

 

[R-Jay]

ok i think limiting the torque to 500 ftlb is going to be a problem with turbo charging.... well not so much a problem, but i think you're going to achieve that much torque way too easily. Reason i say this? because most of the turbo 1uz's out there are making that much torque on tiny amounts of boost... sure each engine is built differently, but there is a familiar story with each...

eg: Justen's celica runs 6.5psi on twin garrett gt28's and makes a smidgen over 500ftlbs or torque (680nm). And as you're probably aware, gt28's are considered small... sortta.. well, they're suppose to flow 400hp each. I understand that his engine was running the standard compression and that using forged low comp pistons will lower torque at the same boost, but you can sortta see that it wont take much to make that much torque....

just thinking out aloud is all.... hehe.

 

[Trvln Nalzmn]

For terminal speed on a car I don't think weight is too much of a factor. It will certainly have an effect on how fast you get up to speed but not on top speed....in theory. The extra power that you'd get from a turbo would far outweigh the weight.

 

[Zuffen]

An earlier post today statedt the 1UZ wieght at 200kg.

This lines up with all the figures I've seen.

 

[928s]

I thank all for their replies, I'm of course aware that the extra weight has no effect on top speed. As far as the weight is concerned it is more about handling and braking and to some extent responsiveness.

As to supercharging V turbos, I actually like the supercharger better but again it comes down to develping too much torque down low. Also if I can achieve 8000 rpm + the supercharger requires a lot of power to run it where the turbos don't. So they are more efficient in that regard. Yes the plumbing is simpler or can be with a supercharger.

As to the torque question again I believe what is relative to breaking parts, is one; shock loadings; two excessive torque at low revs, which is almost similar to shock loadings. What type of revs were you talking about when you mentioned that 500ft pounds? Has anybody got a different opinion?

Cheers Greg

 

[R-Jay]

best to ask JustenGT8 as he is one who has the exact numbers.

my guess is it would make 80% of max torque by 3500rpm on smallish twins... a big single will make it further up, but shock loading would increase....

either way, im sure your gb would be fine to handle it.... btw, what transaxle is it???

 

[928s]

It's a ZF box, there is no danger of the diff part breaking, that is super high tech, the gears are ground from hardened steel as apposed to being cut and then hardened. A very expensive process that for many years was only available in Germany. Its called Klingelnberg palliod tooth system. The diff is an electro hydraulic locking diff similar to what they use in F1 and similar to what the Ferrari 430 uses.


The gearbox gears are also made out of an exotic high strength steel material called 17CrNiMo6 also the gears have been shot peened with wire shot. The problem is the transmission case is made from aluminium, when it gets hot it is quite weak, I have heard of racers, (not with this box) encasing them in carbon fibre. But I have heard of them doing the cryro thing. I will the do the cryro thing if it breaks, no I will just cry.

 

[R-Jay]

ok now that would seem overkill if it wasn't in an exotic car like the 928, hehe... and a little more technical info than i had bargained for, but it's always good to learn something new.... *mental note: porsche gb are cool*

also, what model do you have in terms of year of release???

i think justen would be a little hard to get a hold of.... i'll ask him on the toymods forum...

 

[928s]

Ok my model is a 1984 928s but it has been updated in numerous areas to a higher spec of later models. The gearbox is from a 1990 model. Here is the link to it. Both of then are mine but the bottom car is the one getting the mods. Also this gearbox has syncro on reverse and is the same basic gearbox that was used in the Lamborghine diablo. Does much of the *** stuff have syncro on reverse? This is the first manual I have had for 20 years.

http://www.landsharkoz.com/htm/ggg.htm

You can click on the photo to enlarge.

Cheers Greg

 

[R-Jay]

Here's a pic of Justen's dyno run at 10psi with water injection on. He lost a fair few rwkw's with the water on but it runs safer.... you can work out the torque figure from this i think... hehe, my maths aint good enough, so i'll leave it for someone else.

 

[BlownV8]

If you were going to use the supercharger path, here is something to keep in mind. Superchargers have maximum operating RPM. When used on some thing like a holden 5.7L Boat anchor, that does not rev that well in stock trim, then can use pretty agressive pulleys, and the rpm range of the engine is not that great. As you want to see around 8000rpm, you would have to use a less agressive pulley, and would therefore limit bottom end torque on the motor to some degree.
For example, an autorotor twin screw supercharger has maximum rpm of 13000. If you put this on a ford 4.0lt 6, you only have a max rpm of say 5000, so you can almost use a 3 to 1 pulley ratio to get things going. As the blower would accelerate that much faster than the engine, bottom end torque would be massive. On a lexus engine reving to 8000 rpm, you would have a pulley ratio of less than 2 to 1, which would move the torque curve much higher in the rev range. This is a lot more apparent with centrifugal type super chargers also. Yes they have impellar speeds of up to 80,000 rpm, but most of that comes from an internal step up gear, pulley speed is still a lot lower.

Sorry for the long and boring post, just trying to offer another point of view to scramble your brain with.

 

[skid]

If you were going to use the supercharger path, here is something to keep in mind. Superchargers have maximum operating RPM. When used on some thing like a holden 5.7L Boat anchor, that does not rev that well in stock trim, then can use pretty agressive pulleys, and the rpm range of the engine is not that great. As you want to see around 8000rpm, you would have to use a less agressive pulley, and would therefore limit bottom end torque on the motor to some degree.
For example, an autorotor twin screw supercharger has maximum rpm of 13000. If you put this on a ford 4.0lt 6, you only have a max rpm of say 5000, so you can almost use a 3 to 1 pulley ratio to get things going. As the blower would accelerate that much faster than the engine, bottom end torque would be massive. On a lexus engine reving to 8000 rpm, you would have a pulley ratio of less than 2 to 1, which would move the torque curve much higher in the rev range. This is a lot more apparent with centrifugal type super chargers also. Yes they have impellar speeds of up to 80,000 rpm, but most of that comes from an internal step up gear, pulley speed is still a lot lower.

Sorry for the long and boring post, just trying to offer another point of view to scramble your brain with.

Brainscrambler, just to clarify that a bit more, are you saying a centrifugal would be better in the long run as would be happy with a lower pulley speed, or would it be worse because of...?

M

 

[turboandrew]

Note, that rpm rating is a continuous rating. Kenne Belle actually goes to something like 19k rpm. I was calculating about 2:1 pulley for me, 1UZvvti with a whipple 2.3l/rev, 7500 rpm, max charger rpm of 15k.

Remember, the motor has to turn 2 revolutions to injest its displacment, so, for a 4.0; 1UZ with max rpm of 7500:

every two revs = 4.0l
two revs = 4 revs on the charger with 2:1 pulley
4 revs = 2.3l * 4 = 9.2 liters per 4 revs on the charger, 9.2 liters displaced into a 4.0l motor, roughly 2.3 times the displacement = 19.11 psi "boost".

IMO, going to 15k rpm occasionally on a charger which is rated at 13k continuous shoud be OK. If you were doing a lot of top speed runs, maybe I would be concerned.

 

[Zuffen]

Drop your drive ratio to around 1.8:1 and boost becomes more realistic and over-revving the charger is no longer a problem.

Even with our decompressed engines 19lb is serious compression. At this level you'd be pulling so much advance out of it you would almost have retard.

Chargers shed their telflon coating when overheated (at 19lb an Eaton would be) or over-reved.

I'll be starting at 1.83:1 which should give me 14lb.

Boost pressure is very dependent on air flow. If your engine doesn't flow well through poor ports, flat cams or restrictive exhaust you will have higher boost.

A well prepped engine with clean ports, nice cams and headers will make more power than a simialr unprepped engine at the same boost. The more power you can make at the lowest boost possible is a good thing.

I realise it doesn't make good "Bar Room" story telling to have less boost than your drinking buddy but it's the time slip that counts.

 

[turboandrew]

I will def not be using an Eaton. Primary motivation is what Kenne Bell has done for the Mustangs, 622rwhp on a bone stock cobra motor (cats, exhaust, throttle, AFM, everything except injectors and tuning) on pump gas with an intercooled lysholm/autorotor twin screw at 22lbs.

Of course, I will start with a smaller pulley ratio, probably 1.5:1

I also plan on using 8.5:1 compression

 

[BlownV8]

Skid, did you get your answer??????
Supercharger pulley sizing is almost harder than calculating the perfect cam shaft. For us, it is even worse, as there are minimal plug and play kits out there, unlike the ford/holden engines. I always reckon the best thing to do is start with a 1:1 pulley. Very under rated i know, but a good place to start. This way, you can see how your engine responds to the added drag of the super charger, and the modified torque/power curves, ( although lower than the final result) and see how the whole car responds. From there, step up in small incriments. 1.2:1, 1.4:1 and so on. As pulleys are only about $80 each to buy, it is a very safe way to slowly see what you engine can handle, and what you feel comfortable with. It also alows you to compare pulley size vs boost vs intake temp vs power/torque output.

Well thats my 2c's. hehehehehe