"hot rodding" your 4-cylinder, True or False Options

[thomasotten]

"You can spend as much as $6,500 "hot rodding" your 4-cylinder and still not match the performance of a stock 914 6-cylinder."

This is tech tip 100 from an old AA catalogue. Without this turning into an AA bashing thread, I was wondering what club member's opinions were. I had the opportunity to drive a 74 911 targa for the first time this weekend, and it was a blast.

[davep]

That is both true, and patently false. You could foolishly spend money and get little or no return on your investment, so it could be true. Or, you could invest wisely and get a great improvement, in which case it is easy to beat the 110 hp of a 914/6 engine. I am sure that Jake could easily build an engine for that money.

[skline]

(IMG:style_emoticons/default/agree.gif) I built a 2.6 liter engine for a 71 914 and its putting out about 165HP and the cost was about 3k, granted the engine life will only be about 30k to 40k or so in my opinion but it is way stronger than a stock 2.0 liter six and will blow the doors off it. I would consider that hot rodding, however, the stock 6 would be worth more on the market than a hot rodded 4 cylinder. Longevity and reliability are there with the 6 and not so much there with the modified 4. Its all in what you want to do. This was doing all the work myself by the way which not everyone would do. If you were to have this motor built and installed I could see the price being considerably more.

[SLITS]

Any engine you build for more HP = more heat = decreased longevity unless you devise a method to keep the temps as cool as stock.

[Lou W]

So what kind of improvements can you expect from the 2.0 engine that AA is building on their Extreme 914? Is it worthg it? They have listed the engine parts and modifiactions on week 9. Sorry about not adding the thread, I don't know how to do that. (IMG:style_emoticons/default/ohmy.gif)

[ArtechnikA]

This is tech tip 100 from an old AA catalogue.

well - old is the operative word. it mighta been true then, because there were far fewer upgrade options available for the T-IV.

but this is now, and there are bigger, better engines available now.

[mikester]

A fact that is constantly overlooked in my opinion is weight. A 2.0L 6 weighs quite a bit more than a 2.0L 4. but you can get 100 hp out of a 2.0L 4 I'm pretty sure without spending 6k and without deviating MUCH from stock. Where as the stock 2.0L 6 only put out 110 or so...

So you have to ask yourself. How many HP does it take to move 1 lb and how many lb lighter is a 2.0L 4 compared to a 6? That in my opinion makes it possible for two equal HP cars to compete very easily. Now there is no denying that a 6 is faster off the line than a 4 (stock setup) but on the track, the line isn't the only thing. A lighter car is a faster car all things being equal (except weight).

But, that's just something I would consider in the equation.

When I compare driving my 1.8L to the 911 (3.0L) I still feel like I would be faster in the 914 than the 911 and that I would 'overdrive' the 911 and end up slower.

(IMG:style_emoticons/default/monkeydance.gif)

[ArtechnikA]

A 2.0L 6 weighs quite a bit more than a 2.0L 4.
...how many lb lighter is a 2.0L 4 compared to a 6?

...there is no denying that a 6 is faster off the line than a 4

from 914.6 owner's manual: DIN curb weight 2075 lbs
from the 914.4 Spec Book: DIN curb weight 2139 lbs

( not that i really believe it. )

anybody got DIN curb weights from a 914.4 owner's manual ? let's take a '70 1,7 and a '76 as typical high and low examples ...

a 2,0 /4 has 105 lbs/ft or torque at 3500 rpm, the /6 has 131 at 4200; below 70 mph or so - say - your typical autocross course, it's not uncommon for 2.0 /4's to outperform /6's. the /6 hits its torque peak at about 90 in top gear, and from there to top speed it pulls away. the /4's flat torque in the lower rev range makes it especially good off the line and out of slow corners.

just because i prefer /6's doesn't mean i don't appreciate the /4 ...

[anthony]

Isn't that an old quote? It seems like a pointless debate now with factory sixes worth 3-4 times what a 4 cylinder car is worth. Getting to the same horsepower benchmarks these days seems like it costs almost the same whether you start with a four or a six.

[jgiroux67]

I've never heard that a 914-4 was 2100 lbs. I've always seen that it was under 2000 except for maybe the 75-76 was probably close to that weight.

[Bleyseng]

The early cars were lighter about 1975 lbs with the lighter doors etc.
I have driven a stockish six and my 2056 four (about 115hp) back to back. The four is quicker but the six has all the hp above 5000 rpms that doesn't exist in the four unless you change the cam. The Djet really helps for low rpm torque which mine dyno's out to about 130ftlbs.
The six sounds better too as you have to keep it above 3000 rpms driving around the street.


Geoff

[MXMARK]

I like my big 4 something like 2533 with tons of torque great mid range and good top to 7000. I would like to think the power is in between the 2.4 and a 2.7 six but I only have my Carrera to compare it with 3.2. Build of the 2533 motor 5 years ago under 4k est. I have a 2.0 911 six in the garage but this big four is soo much fun. Watch out Muscle cars. Just Kidding. I do love the sound of both the six and the big four. Thanks Mark