Tacos 4KTQ I0vt Swap: The Red Baron - buying parts again

[AngryTaco]

Yeah should be pretty quick. I would think with VEMS, 7400 K24, W/M combined with my cam, ported head, oversized valves, ported manifolds, and 22psi should net me around 350bhp. 275 wheel would be awesome.

[scubadave]

350 CHP. 275BHP

[my2000apb]

huh

[AngryTaco]

Dont start with me dave.......

[scubadave]

Sorry jared,

Its a subconcious automated response like musle memory. MUST...RESIST...CORRECTING...PEOPLE...

Like having a problem under the hood and not opening it up and taking a look. Total move

[AngryTaco]

Arent BHP and CHP the same thing for the most part?

Id figure 400whp with 350 CHP

[85oceanic]

Arent BHP and CHP the same thing for the most part?

Id figure 400whp with 350 CHP

[scubadave]

CHP = crank horse power

BHP/ WHP = brake/ wheel horse power

For awd reduce chp by 25% and you get bhp for drivetrain losses.

[85oceanic]

CHP = crank horse power

BHP/ WHP = brake/ wheel horse power

For awd reduce chp by 25% and you get bhp for drivetrain losses.

I thought it was only 20% drivetrain loss for AWD and 10% for 2wd.

[scubadave]

Its all kind of general. Across the wide spectrum of awd manufacturers, 25% is a good average. But whatever floats your boat.

[85oceanic]

[Hank]

It is isn't linear, ie, there is a lot more friction and drag on gears at 600whp than at 180whp. I think 20% is good for less than 200whp, somewhere around 24% at around 500whp and 750whp is probably in the realm of 28%

Lots depends on tire selection and pressure. I picked up 30whp at 600whp by inflating my tires to 35psi instead of at 24psi. Car wasn't any faster on the street, it just had less resistance on the rollers. R comps are power robbers too....

[85oceanic]

Good to know Hank. I never knew!

[vt10vt]

It is isn't linear, ie, there is a lot more friction and drag on gears at 600whp than at 180whp. I think 20% is good for less than 200whp, somewhere around 24% at around 500whp and 750whp is probably in the realm of 28%

Lots depends on tire selection and pressure. I picked up 30whp at 600whp by inflating my tires to 35psi instead of at 24psi. Car wasn't any faster on the street, it just had less resistance on the rollers. R comps are power robbers too....

That makes sense but 30whp is a LOT

Glad you got the 4K back together, you've been through a lot of valves! That turbo is going to be awesome I bet fast spool and enough torque to bend 20v rods at the rpm's 20v's prefer should be a great match for the beefy bottom end

[AngryTaco]

I always thought brake HP referred to crank/flywheel hp so youll excuse the misunderstanding.

Yeah I cant wait to get that turbo on here. Should be pretty nutty.

[Wheeljack]

Actually bhp is roughly equal to chp. Both are without drivetrain losses, unlike whp. The 'brake' in bhp isn't your brakes at the wheel, it is referenced to an engine brake used to measure torque at the flywheel. True story.

And it is pretty widely accepted that drive train losses (percentage-wise) decrease with increasing power due to fixed losses becoming an overall smaller percentage of the power. For lower powered awd cars, 25% is generally taken as rule of thumb to convert from whp and chp/bhp. I've seen numbers quoted for higher powered cars in the 20% range.

Just what I've read over the years...

[Hank]

What I spouted off was based on something I read on the geek a while back. I believe Shadzi was the author saying that as you increase power, load on gears, CVS, bearings increase, especially in small displacement motors where input shaft speeds are increased to make hp. This was the rational behind an increasing drivetrain loss percentage. A fixed value would negate these friction losses, nor explain the reason high output(torque) transmissions need oil coolers to displace all the extra lost energy(in the form of heat).

I have never really put much thought to it other than do basic calculations of a stock CQ on the dyno compared to what an 800hp turbo does on a dyno. I could be totally off on this

[Wheeljack]

I didn't mean to say that it was solely a fixed value for drivetrain loss; just that there is a nearly fixed component to the total that is largely independent of total power through the drivetrain. The other portion being some relationship to overall power. Lots of 'speculation' on s2forum supporting the decreasing percentage with increasing power theory. You need a cooler because you are always losing more power with increasing chp, but the losses are just not increasing at the same rate.

It makes sense to me, but I've never sat down and done the maths.

[scubadave]

Well you learn something new every day. I too thought bhp refered to the measurement at the wheels as opposed to the crank. Glad all the smart people live within 500 miles of me. Sorry Marc, guess you need to move to access the circle of smart...

[AngryTaco]

Ill take that turbo now as a formal apology now lol

[loxxrider]

The bhp vs chp being both kinda at the engine agree with what I've learned. I'm not super clear on the difference, but chp seems to be the number to quote if you are trying to make a reference to a conversion between whp and power at the engine. bhp implies some other variables which I'm not too sure of.

As far as the drivetrain losses are concerned... Hank, don't you know you can't trust Shadzi by now?


OK, that might have been a bit of a low blow, sorry

Really though, I'd like to know more about this, but it is one of those things that you have to take some actual measurements on to be sure of your analysis. It'd be fun to engine dyno and then hub dyno back to back to see what the numbers are like on various awd drivetrains and hp levels!

[AngryTaco]

Ive always been under the impression that CHP what the engine makes with no outside drag or loss

BHP is flywheel hp with all accessories on the engine

WHP is wheel.

[AngryTaco]

Dave I'll take that turbo now LOL. I'm getting insane surge that bounces between 13-16psi. I have to control boost with my foot and keep it under 13. If I go full throttle in 3rd or 4th itll immediately start spiking and surging. I now see what you were talking about.

[85oceanic]

Buy the damn thing already!

[40v4kq]

Just a thought (people chime in if you have info too), but i've been told that an audi k24 will not flow enough to cause compressor surge. With that in mind, are you positive you are getting surge? and thats its not something else like a boost leak or some weird issue? I dont understand how a turbo that flows more(volvo k24) would cure a surge issue anyway.