How much horsepower is too much?, for a road car.... Options

[gothspeed]

I don't know what years johannes used but the 2013 boxster and boxster S weigh 2888 & 2910 pounds and have 265 & 315 HP respectively. So just quickly looking at his numbers without a calculator, they appear legit. (IMG:style_emoticons/default/smile.gif)

[johannes]

Maybe I'm missing something (IMG:style_emoticons/default/huh.gif)

example;
If your 914 has 225HP - you are in Boxster S Territory

A Boxster S has 225HP and weighs a Lot more than a 914

A boxster S makes 315 HP in my country ...
http://www.porsche.com/france/models/boxst...aturesandspecs/

...

[J P Stein]

The Shitbox had 200hp RWHP and weighed 1725lbs.
None of those Panzer pigs could deal with it at an AX.....even when more cubic dollars were added to em'.

There is more to quick than HP/weight. Inertia works its way in there...you might wanna write that down some where.

[Woody]

The Shitbox had 200hp RWHP and weighed 1725lbs.
None of those Panzer pigs could deal with it at an AX.....even when more cubic dollars were added to em'.

There is more to quick than HP/weight. Inertia works its way in there...you might wanna write that down some where.

Whats inertia and where can I buy some? (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/poke.gif)

[carr914]

Whats inertia and where can I buy some? (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/poke.gif)

Comes in a Little Blue Pill!

[Rand]

"As much as you can use"

Bingo. The the best concise answer for sure!

The tough question is, how much can you use. I guess that's what this thread is really about.

[Cupomeat]

I remember that when the Porsche 928 GTS came out on the early 90s, and it had 345hp (Final HP) figure, Car & Driver's review said (paraphrasing) that 345hp was too much for a (any) standard shift car, and preferred the car in an automatic.

This suggests that it is all about the control of the power and the smoothness of how it is applied to the ground.

For a 914, I'd say that without significant weigh increase, 250hp is more than you'd ever need in a street car and even then you can get yourself in SIGNIFICANT trouble, upsetting the chassis and losing control easily.

In the right hands (and feet) more can be more fun at time, but hard to use all of it.

To that end, I'll leave with the old adage:
Going fast in a slow car is more fun than going slow in a fast car.

Enjoy

[Rand]

There's never too much power, but there most certainly is a point where more is unusable. How much HP does it take to accelerate from 0-40mph? How much HP does it take to accelerate from 80-120mph? Obviously way different. So it's not about how much overall, but how much you can use at any given point.

I wouldn't want something so squirelly that I couldn't touch the throttle without it going instantly ballistic in downtown traffic. But that amount of power could be usable on high speed straight.

The more power I had, the more I would want to be able to modify the throttle curve. IE, I don't want the first 1/4" of the throttle throw to blast me 800hp. To me, it's not the total HP, but rather the delivery curve. Give me a friendly control and let me use my foot to determine how much I get.

[shuie]

1300 is probably too much. IMHO. YMMV.

[Jgilliam914]

A friend of mine had a 1971 Hemi Cuda with dual quads. The PO had it set up for 1/8 mi drags. That was too much power in that chassis for street driving. You couldn't get the tires to hook up to launch the car. But boy if you did that would have been a fun ride. He tried to sell it to me in 1981 for $2500. Shoulda woulda coulda... (IMG:style_emoticons/default/headbang.gif)

[Randal]

Best all around engine for a street car is a 3.6 IMHO. Very tractable, but crazy fast when you call on it.

But I wouldn't go that way without serious suspension work. And of course that applies to any major HP transplant.

[tadink]

Great discussion - thanks for all who have contributed -

Here's why I asked the original question - there was a car for sale in SF CL that was advertised at "900 HP". I was interested since the build since the parts used seemed first class, and the the engine pedigree was top notch (Keith Black - race engine builder). Turbo V8.

I went to look at it and drive it - and, well, it was as advertised but was in need of serious sorting out. What I found was that the race engine combined with a ZF trans and race pedal cluster meant that it was nearly impossible to drive! The clutch pedal throw was maybe 2 inches, and the lack of low end torque meant that you could hardly launch.

Once you were on the gas and rolling - watch out - went like the hounds from hell. But in between - lack of low end grunt, lightweight flywheel, huge clutch, no throw, etc. made the car completely ridiculous for common drive around town comfort.

Perhaps with some sorting and some clutch pedal work the thing might have been more workable - but the race bred high revving engine was a poor match for the rest of the build.

so, I'll answer my own question, if you are driving in normal around-town-traffic, too much horsepower is probably possible if the build is not well matched to the engine.

I believe the engine torque curve in this instance is probably right for the track (maybe), but starting out on a hill in SF in traffic would be nearly impossible.

I'm now thinking - as result of much of this discussion - that a 3.2 would be just about the perfect powerplant for a semi-practical all around car - some street, able to get thru SF, and decent AX and track beast.

Great discussion - thanks again!

td

[Andyrew]

What color was it, anything you can describe about it? Its very possible some of us might know of the car.

[tadink]

What color was it, anything you can describe about it? Its very possible some of us might know of the car.

It has been kicking around the Bay Area for awhile - white with a fg 'fiero kit' installed years ago. the guy has been building it since the 80's, has a 'miami vice' look about it.

The break-up value exceeds what he is asking for it - on CL for $12k. The pantera transaxel is probably worth $6k, and he's got Fox coilover suspension on all 4 corners. the turbo v8 looks a little cobbled together - think mad scientist.

clearly an interesting source for some really nice parts....but the guy is a bit of a nutter, seriously went off on me when I did not buy the car. lol

may be an interesting ride - but as I said it needs serious sorting out. damn, I did not think to get the vin number for the db....ratz.

td

[J P Stein]

The 2.7L in the shitbox was good AX motor......10.5:1 compression and Solex cams....pretty mild. It was also a fine street motor with good low end grunt/midrange & peak power at around 6400 rpms....but would pull just fine to 7200. No need of light switch clutches & all.....a stock 911 unit.

With a lot of tire, there is usable power.....AND it always ran. It's tough to develop a car that is broke down 50% of the time. Hp is only a part of the overall need of any car and is over emphasized.

Inertia in the from of cornering forces/directional changes was what I wrote about.
The flat motor keeps the CG down low.....ever seen a fast V-8 AX 914?....me neither.Want one? Buy a Z06. You can spend multi-thousands trying to match their capabilities.....and still come up short.

10 :1 weight/hp is a good number......provided you have enough tire. Drop below that and you'll find yourself "into" tire research.....more money spent on black holes.

Ignore the above if you're into "bragging rights".

[FourBlades]

My variation on the question is what tire, brakes, suspension set up works best for what HP range. The set up values are just a wild guess, please post suggestions based on your experience.

Tires are max performance summer street tires or better.

100-150 HP - 205 tires, stock brakes, 100 lb springs, stock torsion bars, stock shocks

150-200 HP - 225 tires, M calipers, 140-165 springs, 21 mm torsion bars, bilstein HDs or konis, flares required, engman kit

200-250 HP - 245 tires, A, S, brembo calipers, etc...

You all get the idea...now please fill this in with the right values.

I know that I have spun my tires shifting into 3rd gear when on it hard with 205 tires and 175 hp 4 banger.

John

[iamchappy]

To much is when you things start to break.....

[McMark]

Great perspective, John! (IMG:style_emoticons/default/clap56.gif)

More clearly states what I was trying to get at. Above a certain HP it starts costing more and more in suspension, brakes, chassis stiffening, etc.

I like your list, and would love to see people's input on those designations.