ALFAGTV6.COM

[Greg Gordon]

With our engines, horsepower and torque are always the same at 5252 rpm. The Alfa V6's redline is above that so an increase in horsepower will result in an increase in torque. So which one is causing the breakage is really a moot point because they will both be going up. In other words even if the problem is torque, a 3.0 with 400rwhp at 6000rpm is guaranteed to have enough torque to break the transaxle.

[Mats]

With our engines horsepower and torque are always the same at 5252 rpm. The Alfa V6's redline is above that so an increase in horsepower will result in an increase in torque.

The Hp is a function of torque and rpm so you can have a falling torque curve but still a raising power curve. In fact that's the normal look in a family type production car.

That's also why in 99.76% of all cars you will have the fastest acceleration when shifting at the redline and not around torque max.

[Greg Gordon]

Mats, I am not sure what your point it there. Yes, of course the torque curve falls off.

My point however is that because the horsepower and torque values are the same at 5252rpm, peak horsepower and torque numbers will be pretty close on a 6000rpm redline Alfa V6. On these engines if you increase power from 300 to 400 horsepower you will get a corresponding increase in torque. Therefore....it's a moot point which breaks the transaxle, horsepower or torque.

[Nikoror]

I think the idea is that torque brakes things in general. So in case you don't have a 6000rpm limit you can have huge power at 12000rpm with very little torque. With a limited budget and a v6 chances are you'll be needing a lot of torque (boost) to brake something. Unfortunately it seems no one knows how much exactly as people either don't try or are embarassed to say they destroyed something

On topic: The Red Verde is great! Torque curve looks awesome, with a 7000 rpm redline this car would be 325+++ rwhp.

I have a few questions: What is your opinion on coil packs and what needs to be done to get rid of the distributor, i.e. what goes in its place? Is it worth the extra $$$?

And what did you do to the central jack point which goes around the sway bar to fit the new sway bar?

Have you had headgasket problems with boosted engines?
Guess that's more than enough for now

Nick
Rice SAE

[Mats]

wtf Greg, are you high?

So what if I have 700Nm at 2000rpm and 120Nm at 5K and falling? What would happen then? Boost remember, create a whole lot of ooompf at low revs (turbo at least). I also thought we were talking gearboxes in general and not just on a GTV6.

[Micke]

Horses create heat - torque breaks things.

[Greg Gordon]

Nikoror: Your 12,000rpm engine example is exactly right. At 12,000rpm the motor is so far above the 5252rpm number that horsepower can be a lot more than torque. Of course that's not the case with a stockish Alfa V6 and that's what we are talking about here.

Back to SuperRedVerde. I didn't set it up for 7,000rpm. The customer didn't want the engine overhauled so I felt a 6,000rpm redline would be a good idea. The shift light comes on at 6100 and the limiter hits at 6250. I am sure I could build a 7000rpm 325rwhp 3.0, but this particular car can't do it safely. I do feel that a bigger heat exchanger for the intercooler, headers and eliminating the converter would bring it up to nearly 280rwhp without doing anything else.

It's very important to retain the central jacking point, especially when working on someone else's car. It can be shimmed so that it fits over the RSR anti-sway bar, so that's what we did.

Installing coil packs is a lot of trouble. Is it worth it? In this case it was because we needed the distributor's location for the intercooler. Would I bother with it on a normally aspirated car? Probably not. We had to make something to go in the distributor's place, and this was not a trivial operation for the reasons mentioned on my site.

The stock headgaskets hold up fine if torqued in accorance with the official Jim K. procedure documented somewhere else on this site.

Mats: I am the one here that's subjected to routine drug testing. No I am not high. I am only talking about the Alfa 2.5 and 3.0 engines. Even so the 5252rpm rule applies to any gasoline piston engine.

You asked "what would happen then". The answer is that for your hypothetical engine, horsepower will be below torque at 5000rpm and be equal at 5252. At higher rpm horsepower will exceed torque. That means this is one weak motor at high rpm. It's not an Alfa V6, probably a large marine Diesel or something else totally off topic.

[MALDI]

horsepower and torque are always the same at 5252 rpm.

This is really just a meaningless artifact of the English system of units. See:

http://auto.howstuffworks.com/question622.htm


Saying horsepower and torque are the same is saying power equals force. Power equals force through distance during an interval of time.

That said, Greg I really love your work on transaxle Alfas!

[Greg Gordon]

Saying they are the same at 5252rpm may not be technically correct. What I was trying to point out is that at this point the torque and horsepower curves always intersect. This is due to the mathmatical relationship between the two.


I think we are starting to loose sight of the key issue I am pointing out. If a 6000rpm Alfa V6 has 400 horsepower, it will have enough torque to break the transaxle. There is no way you are going to have a 400hp motor with only 180lb/ft of torque and a 6000rpm redline. If you were building a 12,000rpm motor you could do that but it's not the case here.

SO....Regardless of whether your transaxle breaks from horsepower or torque an Alfa 3.0 as I described, boosted to 400hp WILL have enough torque to do it.

[Nikoror]

We all know that power=torque*rpm/constant and this constant depends on the units used, so the rpm at which torque equals horsepower (as numbers) varies. However, I think Greg's point is that on the alfa v6 (and any other gasoline i.c.e.) to get a lot of power with a 6000rpm limit you need a lot of torque. Of course it is possible to have a torque curve which starts really high and drops quickly with rpm. This way the engine will not have a lot of hp, but will still likely destroy transmissions. But that doesn't sound like a gasoline v6.

Back on topic:

I have several questions about the water injection:
Is the location of the cold start injector a good place for the water injector? How long can you drive on the track before running out of water? Is it worth going to individual runner injectors or stick with a single one? What intake temperatures are you getting after several runs on the dyno?

Nick

[Barry]

You guys are all saying the same basic thing here...

A big turbo engine will break things...A n/a engine shouldn't..
Ive seen big power turbo`s-2.8l-break a pinion gear right off at Kyalami as it was shifted into 3rd gear..The same car burst a gearbox housing before it was strapped.
Ive not seen a big power n/a engine break anything when driven vigorously but with care..Ive also seen a puny 1800 Alfetta spit the prop out when spun to 6500rpm and the clutch dropped.Fellow also lost the race that way...

[Greg Gordon]

I don't think we are all on the same page here, although we are probably on the same chapter and in the same book.

First of all I want to be clear, we are talking about a 3.0 12Valve Alfa V6.

The point at which the horsepower and torque curves cross does not vary (gasoline piston engine etc. etc.). It ALWAYS happens at 5252rpm. Now a 400hp forced induction (turbo, roots, lysholm) engine could easily have it's 400hp at 5600rpm. That means that it's torque value at 5252 can't be much below that because the horsepower just 350rpm lower won't be that much less and that's where the lines WILL cross.

Now in the case of a normally aspirated engine this would be true IF you could get 400 horsepower out of this engine at 6000rpm. However I don't think even Barry can do that. You would probably need a 7000rpm or 7500 rpm or even higher to get that much power out of the engine we are talking about. Now on this engine, torque could be a lot lower than on the 400horsepower forced induction motor, and in fact probably will be.

Nick, on the water injection stuff, call me. Get the number from Damen or from my wife. Her shop number is on my website. Those questions will take me too long to write answers to. If you are going with water injection we need to talk. I don't think the cold start injector location would be a good spot although that's just a guess as I have zero data to support that theory either way. Those other questions are highly complex.

Greg Gordon,
www.hiperformancestore.com

[Mats]

Sure we're on the same page, we're even in the same paragraph. It's just the regular forum type talk i.e. a mix between the original thread topic and a general quastion asked that is answered in a general way and not constrained to the thread topic. Then the confusion begin...
Add some trash talk (that's me ) and you got yourelf a small issue.

That being said I think you are still missing a point Greg, the torque/hp are only represented with the dame digits at 5250 if you use foot-pounds and hp. With Kp/hp, Nm/h or Nm/W you will have a different number at which the graphs cross. That's what the gang has been saying.

[Greg Gordon]

I don't think I am missing the point. The point is that an Alfa V6 with 400hp at 6000rpm is going to have a lot of torque. This is true regardless of what system of measurement you use and regardless of what method is used to get that much power (with the exception of course of something that increases boost a lot from 5252rpm up to 6000rpm).

If I am wrong show me a dyno sheet from any internal combustion gasoline engine that proves me wrong. I think any charts you find (excepting systems that increase boost radically with rpm) will show a peak torque value of at least 75% of the horsepower value at 6000rpm. In other words if the engine has 400hp at 6000 rpm I say it will have a peak torque of at least 300 lb/ft. I could literally show dozens of dyno charts to support this.

[ar4me]

What Mats and some others are saying, is that it depends on the unit you use for power and torque. Try use inch-lbs (or yard-lbs ), and the 75% number change dramatically. Just add a UNIT to your torque to power ratio and it makes sense.
Jes