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Posted by: tadink Apr 19 2013, 05:28 PM

Hey all -

I've been looking at options for increased HP and have run across some crazy stuff, and that got me thinking about "how much is too much"?

This would be an occasional track car, AX often, mostly street, preferably reliable.

I've seen recently, in no particular order: 3.2L pretty stock, 3.3L race prepped turbo, 2.7 or 2.8 race prepped, v-8 twin turbo , and other various mixes of suby-turbo, McMark's turbo 1.7L project, etc etc.

so, for you high HP guys out there - when does the car get just too silly to be practical on the street? 300bhp? 400bhp? 600bhp? 900bhp?

and what makes it not so enjoyable to drive around 'normally'? One guy described his 2.7 race engine as just too high strung for the street - - - so that means that you have to get into higher revs to get the power from the cam?

edumacate me pls......

td

Posted by: rick 918-S Apr 19 2013, 05:49 PM

350+ doesn't seen to ben an issue...

Posted by: iamchappy Apr 19 2013, 05:53 PM

I think 400 is fine, takes a little getting used too, but is very streetable.


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Posted by: GeorgeRud Apr 19 2013, 06:07 PM

As Mark Donahue stated, "when I can spin the tires in top gear at the end of the straight"!

Actually, it's more fun to pull away from "muscle" cars through the twisty bits. Just about anyone can plant their foot on an accelerator.

Posted by: kg6dxn Apr 19 2013, 06:16 PM

Autocrossing with big HP in a small car is a challenge. Big torque is an even bigger challenge. I have had from 250hp up to 500hp in a 914. The 250-325hp seemed to be the sweet spot for a mild conversion. If you go much higher, you will need flares, big tires, big brakes, stiffening, etc...

Here is a video of Andyrew drifting his 383ci V8 914 around a parking lot. With a big torque motor, this is what happens at an autocross. This is fun but not a way to get a competitive time.


https://www.youtube.com/watch?v=tOJf7PpP4l0


I am building my conversion to be in the 325-350hp range right now. I'm keeping the factory ECU flashed for big injectors and turbo. The plan is to make it totally streetable with plenty of mods to take to the track.

.

Posted by: euro911 Apr 19 2013, 06:21 PM

Shit, I'm happy with 125 ...











... but 200 would be nice

Posted by: The Cabinetmaker Apr 19 2013, 06:25 PM

Richard Fisher has about600 in his car. I've ridden in it, and drove behind him in the twisties.
He has no trouble with either of them. I had my foot in my 4 hard just to keep up with him on talimena drive. Too much hp? Not!

Posted by: ConeDodger Apr 19 2013, 06:56 PM

225HP is very fun and streetable... Idles well, handles traffic without complaint.

Posted by: carr914 Apr 19 2013, 07:08 PM

Depends on the car & what the Induction is. I've driven 600+HP cars on the Street - No Problem. I've been around 250HP cars at the Track that I wouldn't set a foot into.

Then there is the Driver Equation! The fact that Car Companies make 600+HP cars that the Average Schmo can buy is a recipe for disaster!

Posted by: iamchappy Apr 19 2013, 07:18 PM

When i built up my car i did it because i wanted to do it, and had wanted to do it ever since they built the 911 turbo, but another reason was to make it run away from the Porsche owners cars that have always looked down their noses at us 914's...
Of course there are plenty of built up Porsche's out there that will out run my car, but i would still give those a respectable fight......

Overview - a torqued out 220 hp car or a 300 hp 3.6 would satisfy just about any of us 914 owners...

Posted by: JmuRiz Apr 19 2013, 09:09 PM

Just my thoughts...I'll have more insight later this year...but I think a hot 2.7 to a stock-ish 3.2 will be great in a skinny fender car. Up to 3.6 with flares and the associated tires. I'm hoping for ~180 with my engine, it should feel like a rocket compared to my previous ~100 /4

Posted by: messix Apr 19 2013, 09:10 PM

imho
it's how the power is made. a high strung small ci 150hp engine that makes it's power in a narrow power band would be a bitch to drive around in traffic.

then if you had a large ci engine that makes monster torque low in the rpm range would be a handful trying to drive on the streets.

if you had a balance of a well mannered engine that made reasonable torque and power in the low end and then progressively more power in high rpm to 400, 500, 600, hp as long as it would be progressive and predictable.

with modern engine management systems including turbo's it is possible to have a very high hp engine that will behave and well mannered to drive around like a Honda accord when needed.

like Jake says "it's all in the combo"

Posted by: Dave_Darling Apr 19 2013, 09:24 PM

I think the answer to "how much power do you need" is always "a little bit more than you have now".

--DD

Posted by: Spoke Apr 19 2013, 09:46 PM

282HP is enough to get me pulled over by the PA State Police at over 140MPH.

They couldn't keep up with me to get a speed so I got off with just a warning.


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Posted by: McMark Apr 19 2013, 09:57 PM

I think 175-225 is the sweet spot. More than that is fun, but you get into diminishing returns after 200, IMHO.

Posted by: Madswede Apr 19 2013, 10:28 PM

I'm breaking in my 3.2L twin-plug, big cam, 10.5:1, PMO ITB, Megasquirt setup right now and I can say (though I'm at a mile high altitude) that it's an utter joy to drive and can be driven around town with ease.

In fact, my setup idles so low and can be so polite, it's a bit of a problem. I forget easily what really lurks behind me in that engine bay. I'm surprising people (including myself) with how quick she can be. How quick she always WANTS to be! If it were more aggressive, I think it would be like a crack-crazed kitten rather than the fun but still kinda wild puppy that it's like now.

This is really a question that can only be answered by you, the driver and owner, and the amount of $ you want to can spend. There is always going to be someone with more power and money and huevos/insanity than myself out there, so I went a certain way down that path and am not regretting it at all. So there's my $0.02 worth.

Oh, and my car has not be dyno'd yet, but it's probably around 285hp at sea level, says O'Brien.

Posted by: Andyrew Apr 19 2013, 10:29 PM

Autox? You wont get much benefit from over 250hp given good tires. Track? Depends on the track and the suspension setup, but the chassis doesnt take over 500hp very well.

I think 300-400 is a really good range.

The problem on the street is to much torque, As you can see in the video above you never even heard the engine in the video as I never got much over 1/4 throttle... But keep in mind that was on concrete. The car looks very similar to that at an autox with full throttle, but also keep in mind its built to drift at a whim as thats how I like to drive. The video above is of the car with about 300hp and 380lbs of torque.

I dont think over 300lbs of torque is really advisable, the real fun here is horsepower with a nice torque curve that lets you get on the gas predictably.

I think that this chassis really benefits from a large displacement v6 or a medium displacement 4 cylinder turbo that revs high (think 7.5k) and has enough torque to pull strong from 2500+. Examples being a porsche 3.6 or a modern 1.8-2L medium sized turbo.

Posted by: Cap'n Krusty Apr 19 2013, 11:24 PM

Hmmmmmm. A wise and admired driver once said something like: "If you can burn rubber from the exit of one turn until you have to brake for the next one, you have enough horsepower". He said nothing, however, about too much horsepower. IMO, having too much HP is like having too much garlic; It can't happen.

The Cap'n

Posted by: messix Apr 20 2013, 12:39 AM

"if everything seems in control, you're just not going fast enough!" Mario Andretti

Posted by: SirAndy Apr 20 2013, 04:36 AM

I've been in a (street legal) 914 with over 1000hp.

"Too much" doesn't even begin to describe how i felt about the car.

If you like a full body workout while 100% concentrating on not losing control the whole time all the time instead of enjoying to drive, then by all means, go for it.

Posted by: pcar916 Apr 20 2013, 07:47 AM

An hour after I "finished" installing my 3.6 I wanted 100 (arbitrary figure) more hp.

Fact is that if the throttle is easily modulated, the suspension/brakes are built to match, the tires are proper, the tub is stiff and the driver has self discipline, I think ~400-500 is a good place to be... more options there. But then realistically, I'll probably want more.

Any driver pushing their skill-envelope in any 914 is gonna spin it somewhere/sometime. As far as I'm concerned, track training should be mandatory for all folks in a mid-engine car. Better to find those limits where there be runoff! That said I think money spent on suspension and driving experience has better returns on the dollar.

Curves are where it's at. I want to sling the paint off of my doors in turns.

Posted by: Phil Plummer Apr 20 2013, 08:39 AM

Hey does anybody know where there is a tutorial video on instalation of metal fender flares ??
not many custom shops around here.

Posted by: gothspeed Apr 20 2013, 11:12 AM

I usually think about it in power to weight and how that weight is distributed on the chassis. There are certainly big hp motors out there but in the case of V8s i think they carry too much weight for the chassis. IMO the weight of a four with the hp of a six (125-200 hp) is an ideal combination.

About 1 hp per 15 pounds of total weight is on the mild side, 1 hp per 10 pounds of total car weight is very nice for a street car and the closer to 1 hp per 5 pounds you get, the closer you are to a track / race car.

Posted by: messix Apr 20 2013, 11:40 AM

an all alloy ls series v8 is not much heavier the a Porsche 6!

Posted by: mr914 Apr 20 2013, 01:14 PM

Simple answer by the late and great.


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Posted by: ThePaintedMan Apr 21 2013, 05:38 PM

I saw a bunch of those a-holes at the PCA DE this weekend T.C. Too much car, not enough talent. It seems like there are more and more guys like this - who have plenty of money to go out and buy a car that they'll never have enough talent to truly drive. Sad really.

That's why I like my car. I'm literally forced to learn driving mechanics from the ground up. And hopefully T.C. will come give me some pointers in May?

Posted by: r_towle Apr 21 2013, 06:22 PM

I,m sorry, is this a trick question?
I don't understand...

Is the original poster of the female gender?

Posted by: johannes Apr 22 2013, 05:36 AM

The 914 is a very light car compared to modern panzers...
Power to weight ratio is what will give you the best information about the performance compared to modern cars...

When your 914 has:
190 + hp you are in Boxster Territory
225 + hp you are in Boxster S Territory
230 + hp You are in 911 Carrera Territory
260 + hp You are in 911 S Carrera Territory
300 + hp You are in GT3 territory ... Scary ! better update brakes, suspension ...

Posted by: sean_v8_914 Apr 22 2013, 07:59 AM

horsepower and money...
"I,m sorry, is this a trick question?
I don't understand.."

Posted by: badmiata Apr 22 2013, 03:02 PM

So a Subaru Sti with 300hp / wrx trans and gt flares would give you the power to weight of a GT3?

Posted by: JmuRiz Apr 22 2013, 03:47 PM

I would think that would weigh more, closer to the 911s

Posted by: gothspeed Apr 22 2013, 10:06 PM

Good Post johannes! It is also worthwhile to note, that every single one of those cars listed in Johannes list, has better suspension, chassis ... and .... brakes that are at least TWICE as good as on most 914s ....

Posted by: a914622 Apr 22 2013, 10:45 PM

Well I will pipe in. Its not the hp its the tork baby. I have a SB chevy 302 with injection and one coil per plug, alum heads ported and polished, long runner headers. I set the computer to turn off spark and fuel a 6500. It revs like an electric motor from 1500-6000. I built the same motor for a life long chevy guy and after his first launch he PUSHED his nova back in the garage and said I will never drive that car again, and he didnt.

And yes it is to much for the street!! Even with 993 brakes there just isnt enough tire to go or stop..I shifted 3 to 4 at 70 and i could boil the tires with the right foot.

So im stuffing the svx engine in hoping for a good 250 with good usable power. I would think one of the modern subys with the VVT system and a huge torque curve would be perfect for the 914 chase? What did they win Lamons with 210 hp?

jcl

Posted by: J P Stein Apr 23 2013, 12:04 AM

Brit finally blew the 901 ....12 inch slicks on concrete at a pro solo.
I finger that 350ish hp/torque was too much.....for the trans.

Add a bunch of power to a 914 and all you'll get is tire smoke. Couple that with tires and then you find the weak spots in the drive train and chassis limitations. Work at that long & hard and you'll find suspension limitations.

IMO, the answer to the original question is "As much as you can use"

Posted by: rfuerst911sc Apr 23 2013, 03:41 AM

I have aprox. 225 hp out of my 3.0 SC motor in my GT clone and I'm happy with the performance. With 911 M brake calipers/rotors she stops good. For me I don't think I would be comfortable driving her with too much more power as getting the tires to hook up when on the throttle hard now is an issue. Better rubber would help and I need to do that.

Posted by: DBCooper Apr 23 2013, 06:28 AM

A lot of wisdom in the answers here. I have probably 260 crank HP, maybe a little more, with 215's, Koni's and Carrera brakes. In a narrow-bodied car and at my age with those tires on public roads it's all I can really use, but I wouldn't turn down more. It's sweet, but it's not too much.

Funny thing, though, I've driven momentum cars all my life, never point and shoot, and I think that adding HP changed the way I drive the car. Now I'm firm but probably not as fast in the corners as I was. I think it's because now that I have the power my mind tells me I don't need to get as close to the edge in the curves because there's always a straight coming up, and I now I look forward to straights. I haven't changed weight or weight distribution, so the car handles exactly the same, it isn't that. It could the way the turbo engine builds boost, it could be my age, whatever, but I suspect it's mental, from just that addition of power. It's not something I anticipated, so it's strange. Might explain why those Corvettes are never as fast as you think they should be.

Posted by: carr914 Apr 23 2013, 06:33 AM

Except you didn't factor in the Weights of the Cars - any 914-6 will be at least 500-1000lbs lighter than the cars listed

Take Weight Out - Go Faster!

Posted by: johannes Apr 23 2013, 06:40 AM

Oh yes I did. I even calculated the Din vs CE Weight for the new cars...
Do your maths...

Posted by: johannes Apr 23 2013, 06:46 AM

If you can keep the weight of the 914 between 900 and 910 kg the answer is:
Yes Sir

Posted by: carr914 Apr 23 2013, 07:04 AM

Maybe I'm missing something

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

Posted by: gothspeed Apr 23 2013, 07:27 AM

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.

Posted by: johannes Apr 23 2013, 07:31 AM

A boxster S makes 315 HP in my country ...
http://www.porsche.com/france/models/boxster/boxster-s/featuresandspecs/

...

Posted by: J P Stein Apr 23 2013, 07:36 AM

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.

Posted by: Woody Apr 23 2013, 10:36 AM

Whats inertia and where can I buy some?

Posted by: carr914 Apr 23 2013, 10:47 AM

Comes in a Little Blue Pill!

Posted by: Rand Apr 23 2013, 11:48 AM

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.

Posted by: Cupomeat Apr 23 2013, 12:00 PM

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

Posted by: Rand Apr 23 2013, 12:34 PM

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.

Posted by: shuie Apr 23 2013, 01:07 PM

1300 is probably too much. IMHO. YMMV.

Posted by: Jgilliam914 Apr 23 2013, 01:13 PM

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...

Posted by: Randal Apr 23 2013, 01:24 PM

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.

Posted by: tadink Apr 23 2013, 10:03 PM

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

Posted by: Andyrew Apr 23 2013, 10:07 PM

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

Posted by: tadink Apr 24 2013, 04:56 AM

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

Posted by: J P Stein Apr 24 2013, 08:44 AM

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".

Posted by: FourBlades Apr 24 2013, 09:03 AM

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

Posted by: iamchappy Apr 24 2013, 09:26 AM

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

Posted by: McMark Apr 24 2013, 09:29 AM

Great perspective, John!

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.