Yet another C20XE/LET post.

cpd · Post by **cpd** » Sat Mar 04, 2006 10:06 pm

Anyone know how different these two engines are apart from the turbo? I'm thinking if I can get an XE, turbo it out...?

I think I heard someone say 6 pounds of boost?

Main reason is:

Much easier to get an XE. Much easier to put it in. Get the XE and F20, dump a turbo on it running the same boost that the stock LET does, so in essence have an LET, but MUCH easier to do and get.

MMamdouh · Post by **MMamdouh** » Sat Mar 04, 2006 10:12 pm

i think the C20LET internals as well as the compression ratio are different but don't quote me on that.

MMamdouh

cpd · Post by **cpd** » Sat Mar 04, 2006 11:01 pm

Aww, dammit.

norman · Post by **norman** » Sun Mar 05, 2006 9:56 am

moin,

make a choice: turbo or no turbo. to fit on the XE a turbo becomes more expensive than to buy a LET. the "XET"

will never run without problems. i?ve seen some kompressorkits for the XE, but also expensive. a nother question: more than 200HP for a frontwheeler the best decision? i drive, when it runs sometimes

, a stock XE in the nexia. with tuning you can get 180-200 HP, and that is good enugh.
the fight with the car on the street begins around 200 km/h. over it, not really funny...on the clock topspeed is 228 km/h

tschau norman

cpd · Post by **cpd** » Sun Mar 05, 2006 10:07 am

I think my speedo goes to 180? Heh.

Hmmm.

EDIT!!!!!!!!

My plans include an intercooler too! Less heat!

Joso · Post by **Joso** » Sun Mar 05, 2006 12:01 pm

I think norman made a point that shouldnt be overlooked. A turbo plus an intercooler means more power at the expense of some response. Ask yourself if you really want that much power in a front wheel drive car. And don't forget to consider fitting an LSD if you go that far..

debo890 · Post by **debo890** » Sun Mar 05, 2006 2:22 pm

sorry to say, but you are a little wrong joso. you dont loose responce with a turbo setup. your car will run normally( like with out a turbo) untill the turbo kiks in. within the point where the turbo is building up boost is called lag. lag is how slow your turbo responds after the gas pedal has been depressed.
also, the xe engine has the same internals as the let. the let just has a lower compression piston. rods, etc. are the same. heads might use different valves. you can either get the pistons off a let or get aftermarket forged pistons(best option if high hp is in prospective).

Joso · Post by **Joso** » Sun Mar 05, 2006 4:21 pm

debo890 wrote:lag is how slow your turbo responds after the gas pedal has been depressed.

So am I wrong or right? how slow the turbo responds = how bad the response is. You are saying the same as me but with slighty different words.
The biger the lag, the lower the response. That's what I meant.

Post by **PrecisionBoost** » Sun Mar 05, 2006 4:40 pm

I tend to agree with Debo about the response.... the lag in a turbo car can be minimized if you do it correctly

If you have a turbo engine making 180hp racing the identical vehicle with a N/A engine making 180hp the turbo car will leave the N/A care in the dust.

If Tom were to post his C20GET powerband you would find that he's making maximum torque at 2400 RPM.

So.... the turbo motor and N/A motor would be nearly identical in power up to say 2000 RPM.... then the power readings for the turbo car go straight upwards to close to the maximum torque.

Given horsepower is just torque multiplied by RPM divided by 5252 you can also predict that the horsepower is going to jump straight up as well.

Recently we were comparing each others cars at our friend's dyno shop and we put up the graphs my friends heavily modified 185whp all motor Neon ( 2.0L ) and Tom's turbo C20GET (2.0L) on the computer screen.

The difference was crazy..... in lower RPM areas Tom was making 100 to 125 more horsepower.

So yes.... turbo cars have lag..... but what we call lag is just the regular horsepower of a naturally aspirated vehicle prior to the turbo spooling up

Now as far as the XE engine having the same internals.... I somewhat disagree slightly....I think it depends on the model of XE you pick up.

From what I remember... I think some XE's came with a 6 bolt crankshaft (like the C20GET) and some came with the 8 bolt crankshaft (like the C20LET )

My guess is that the 8 bolt crank (on the flywheel) is stronger than the 6 bolt crankshaft....... now having said that.... there are a few guys pushing the C20GET up into the 400hp range with their stock 6bolt crank.

So.... unless your planning for more than 300hp.... I wouldn't worry about the difference in crankshafts.

The C20LET has low compression pistons ( think it's 9:1 ???) and the XE had something like (10.5:1 ??? ).... I'm not sure.... it was something like that.

I would agree that anything over 180-200hp is going to be somewhat useless in such a light car.

My turbo Optima (aka Lemans/Astra MK2/ Nexia ) has a hard time getting traction in 1st and 2nd gear... it's not until 3rd that I can stomp on the throttle.

Without an LSD things can get crazy.... I had situations where one tire would start spinning pulling me one way and then all of a sudden the other tire lets loose and the car quickly jerk the other way..... so it was a real handfull to keep it going in a straight line.

If it were me..... and I had access to a cheap C20XE.... I'd buy a set of gently used C20LET pistons.... drop them in and turbo it up ( 8 to 10 psi )

I'm pretty sure Tom has aftermarket turbo manifolds for the XE..... but I could be wrong.

If you can find a C20LET manifold with turbo you would probably be able to get it relatively cheap.

I found a C20LET at an australian autowrecker about a year and a half ago.... the guy wanted $4000 USD for the engine and it had 120,000 miles on it!!!!

I would guess the shipping would probably be another $1000 to $1500 on top of that.

For that price I could probably bring two or three LET's from Europe.

Joso · Post by **Joso** » Sun Mar 05, 2006 6:35 pm

chris@PrecisionBoost wrote:So yes.... turbo cars have lag..... but what we call lag is just the regular horsepower of a naturally aspirated vehicle prior to the turbo spooling up

Not exactly. Lag is the amount of time since you press the pedal until the engine works how it should. Secondly, the power in the same engine, with and without a turbo is not the same when the turbo is inactive (in the turbo engine). And the turbo may make the ride more diicult to drive, maybe unpredictable if the boost is big.
I really can tell you that a highly tuned, racing 2.0 turbo car with 400 hp is more difficult to drive than an N/A, big displacement stock car with 400 hp.

Maybe you don't mind it at all, because you like to do 1/4 miles, and drive in straight roads, etc. (Im just guessing, I dont know you at all) but for me, the performance in corners is important.

chris@PrecisionBoost wrote:I would agree that anything over 180-200hp is going to be somewhat useless in such a light car.

My turbo Optima (aka Lemans/Astra MK2/ Nexia ) has a hard time getting traction in 1st and 2nd gear... it's not until 3rd that I can stomp on the throttle.

Well, The problem is not the weight. The problem is it being FWD. FWD + more than 200 hp = massive understeer. That's the main problem.

chris@PrecisionBoost wrote:Without an LSD things can get crazy.... I had situations where one tire would start spinning pulling me one way and then all of a sudden the other tire lets loose and the car quickly jerk the other way..... so it was a real handfull to keep it going in a straight line.

I totally agree you on this one.

cpd · Post by **cpd** » Sun Mar 05, 2006 8:20 pm

Well... Was thinking not to push it out at all. Just the XE, so 110kw, plus a turbo, but not too big, and then don't push it more. So hopefully a max of 180-200hp, or 150kw TOPS. ABSOLUTE TOPS.

I don't want to boost it big, just enough for a bit of a kick. To be honest I don't know how many psi that would be, so who knows? I'd have to make enquiries, etc.

I realise there's different crankshafts, but if I'm not making my XE out to like 300kw, I hardly see how it matters. If it's only a bit of a power gain, then things should be fine.

Straightline stuff is more what I want the hard take-off for, however corners is good, but I'm still sourcing a strut-bar for my 1.5i. I've found one, just gonna cost a pretty penny, shipping from the UK and all (strutbracer.co.uk). And then I've gotta get a higher flow fuel pump and try and get my fuel tank flushed, I think there's shit floating around the bottom.

So as I've said: Pretty much, XE + turbo, not too boosted, nothing ridiculous, just a lil bit of a push. Should handle it fine, right?

Stefan · Post by **Stefan** » Sun Mar 05, 2006 9:01 pm

Use the XE. Only things you'll need to swap is the pistons, or if your short of cash use a compression spacer. The stock XEs rods, crank, head and cams are fine.
For the turbo and manifold contact this chap http://www.mvaux.com/turbo_kits_for_calibra_vectra.htm (you can buy the parts seperately) or make it yourself. Quite easy really (though a bit old school) and would suffice for 250-300hp with an intercooler.
Need any more advice let me know.

Stef

MMamdouh · Post by **MMamdouh** » Sun Mar 05, 2006 10:15 pm

just a question concerning turbo setup... when the turbo is not spooling at low RPM; won't it - as well as the intercooler - put some restriction in the passage of air going through the intake??

i know you won't turbo your car to cruise at 1500 ~ 2000 RPM, i am just asking from the pure point of view of physics here.

MMamdouh

ubuyau · Post by **ubuyau** » Sun Mar 05, 2006 11:14 pm

So far as NA vs boosted applications - the way i see it is that the NA motor will have constant lag - since you never get boost anywhere in the rev range.

The boosted engine will probably be slightly less responsive before boost since it has the air restriction of the turbo - but this is probably negligble. The boost makes up for it

I think choosing the right matched turbo for the application is important. Too big and you'll make alot of power in the top end but be slow down low. Too small and you'll run out of puff in the top end. The TD04 on the 1.5L is great for twisty hill climbs - it seems im almost always on boost! But that said, in a straight line on top end i feel it runs a bit out of breath - nothing a bit more boost wouldnt fix

I never realised the XE had such a high compression ration 10.5:1!

My opinion for turbo would be something like a T3 @ about 6psi on the 2L? With suitable fuel mods, etc. Should give nice responsive down low power

--Tim

DomWoo · Post by **DomWoo** » Mon Mar 06, 2006 12:02 am

just because a turbo is below boosting RPMS doesnt mean that it is not spooling.. i would say on a decent size turbo like a t3 at 1200 rpms is pushing enough air where there is no restrictions in the turbo charge pipes/ intercooler

i got 2 lanos's both with a 1.6l

one is turbo and one is not

the N/A engine is SLOW right off the line and stays slow, to tell you the truth i think it sucks!! and i dont like to drive it.

the turbo lanos has a bit hesitation when the gas is pressed but no more then the N/A engine, but as soon as it breaks 1500 rpm it takes off like a rocket and doesnt stop

now this is how i see lag.. take 2 of the same turbo vehicals like an egale talon and upgrade one with a huge turbo so that it can boost to 20 psi but with the other one you keep stock with the 16g's turbo and its only boosting to 14 psi

its going to take alot longer to get the huge turbo to even begin boosting as with the stock 16g's turbo starts at 2k rpm and instantly makes more power

now i would say that the upgraded egale talon has lag because it takes longer then stock to make more power

thats just how i see it.. i dont consider taking a N/A motor and turboing it to have lag because it is performing better then the stock motor