Hello people.

I'm a noob here, but been around cars for awhile.

Recently acquired a 75 914 that is very clean and going to do the Subaru conversion. Car will be used mostly for track events and some odd miles on the street.

The question that I had, is how does this car respond to high horsepower? In stock form, the EJ257 will put out 300 at the crank and I'm wondering if it makes sense to tweak it a little more....

I've seen a few conversions done here and read through a ton of threads. Some very helpful info here, but I haven't read anybody's feedback on what the chassis will do if throw 500hp at it? Besides all the supporting mods necessary to handle the power, what will the driving dynamics be??
Maybe it's not worth to do anything except just the engine swap, but since it's going to get a full cage, big brakes and aero, maybe go big

David

Sounds really expensive ,buy one already done for less than half.Save yourself alot of time and money.Ballpark, for what you are describing ,you are looking at over 30,000.Jake sold a real sweet car here with 140 h.p. for under 9,000 that was good to go,and I am sure it was pretty fast too.So, do you wanna drive, or do you want a hobby??? Are you a race car driver???Jason

Only people I recall reading about that have anywhere near that kind of HP have full cages and a 914 shell. I am sure others will chime in. I certainly do not think the 914 needs that kind of HP as it is a very nimble car. You add a ton of HP to a nimble car and you make it not so nimble.

Good luck on the build and I look forward to seeing your progress.

Nope, doesn't make sense to tweak it a little more. I had around 300hp in mine (before theh engine broke) and it would up and mooove. Then again, I'm replacing that V6 with a twin turbo unit to go for the more hp. I am sure it doesn't make sense, but I'm doing it anyways since I have the engine.

Thanks for the replies.

Unfortunately, i stay in the states for only a part of the year, so this build will be at the fab shop for a while...
I def plan on doing a full cage and some sort of wide body. Just not sure exactly what.
Eng/trans will ne about 10k all in, rest will be chassis work.
Hopefully it will be done when i get back.

What is everyone running for suspension?


Yes, i have raced cars in a previous life.

the 300 hp area is a very fast car.. Suspension and chassis improvements, check with Tangerine Racing/ Racer Chris is a member here.

Tangerine Racing, Rebel Racing, Tarret etc all have parts and such that you would need.. The 914 is meant for a road course.

A momentum car can be alot of fun. A high hp/high speed car adds complexity to the race course. Again 500 hp for DE's most would say is overkill.. Then again some here have those cars.. The learning curve on that kind of car is much greater. Driving and tuning..

All being done by a shop,,,,,,very expensive

That being said I putting in about 300hp in mine also.. ej20k..

300 HP is a VERY fast car. Start pushing 400hp and you need to get some serious tire under the car to keep it on the ground. at THAT point, you need a strong trani/cv's. Which you then need to reinforce the chassis quite extensively, a cage will do if its tied into the correct points.

Suspension for a 500hp car? At that point most of the race cars have some custom suspension. Typically you just need to determine what kind of driving you'll do and tune the suspension for that.

IMHO with a turbo engine this is the way I would go.. If you have the money, build the engine for 500hp, Lower the boost down so your at 300hp. Drive it for 6 months. Add 50hp. another 6 months, add 50more.. ect.
You'll respect the car more and you will learn what changes are needed as you go along.

The Factory Drivers were afraid of the GTs when they were approaching 300 HP.

I'm going to have more than 300, I have to see how big my Brass ones really are.

T.C.

I got to say I am very seriously considering the ecotec motor with the pdk transmission. The stock ecotec in my solstice I got it tuned and it makes a very reliable 400hp or close to it. Figure 20k to do it.

There have been a number of 500+ hp V8 conversions. Like Andyrew said, when you're in that range, you'll need overall stiffening, and a cage tied to the suspension, along with a few other reinforced pieces will usually suffice. Of course, you'll need bigger brakes, stronger trans, stronger axles, wider tires, etc. etc. But the design of the suspension is good for plenty of power and can be tuned fairly well for whatever type of racing that you're planning . You don't have to go as far as a tube frame race car with 914 panels tacked on the outside, unless you want to...

I have reinforced everything, inner long kit, outer long kit, swing arms, all the areas on and around the suspension console without the rod bracing. I also have a bolt in roll bar that's not used on the street. 944 turbo brakes on all corners. I think i have around 400 hp. Unless your looking for an all out race car, 400hp is getting close to the safe limit on street driving if you plan on standing on the throttle once in awhile. The world passes by very quickly in a 400 + hp 914. I can tell you it has had my heart racing more than a few times, in fact almost every time i go out for a drive....

I've been running a 993 engine in my 914 since 1999 and wouldn't ever go back to less horsepower. It is spec'd at 270hp by Porsche and I have a clutch/flywheel assembly that weighs in at almost 20lbs. The stock 993 flywheel and clutch assembly weighs right at 55lbs. That makes a big difference in how the car ramps up on power, but is very driveable since the DME helps. With carbs that would be a different story (on the street) when the engine was cold and at very low revs.

The car has to be stiffened, the suspension must be beefed up, the brakes have to be bigger, and on the track and street you should really consider a limited slip differential (although I didn't have one until many years after the conversion). I could easily use another 100hp... period, but not at an AX.

Good luck!

I'm trying to help set up a 500 hp 914 for A/X right now.
With the street setup it currently has, the car is practically undriveable with any more than half throttle.

2,200lb car with 500hp will be a point and shoot car. there will be so much acceleration that if you can get the traction you would spend more time trying to get it slowed down and settled for a corner then you would be on the gas!

tc9148 has a 400+hp v8 car and i drove it.... brings big smiles. but that kind of car takes a while to get used to what the limits are and the consequences on going over at the kind of speed are not friendly to your health.

http://www.negativereinforcementracing.com/

track car - 500hp and wide body - what is your budget?

When they first created Street Modified in SCCA I was using a turbo civic with 350hp at the wheels. Almost uncontrollable at autox. Thankfully I had a boost controller and could turn it down to about 250hp.

It was still what I considered a point and shoot car. It was setup so the rear would rotate around corners and this allowed me to get on the gas faster. Very weird and twitchy setup but I was winning like this.

Another interesting characteristic is that with big horsepower, you'll spend almost as much time shifting as you do accelerating. But it's fun. The transmission, clutch, and shift mechanicals have to be in tiptop shape all the time.

140 HP = 130 MPH

Here is one for you. twin supercharged V8 914 I am not sure how much power it has, can't remember if it was 750 or 1000 HP

Hope you have a lot of money to spend. Sounds like a fun project

I think with so much power its not really useable unless you have some kind of traction control or AWD system. That I would like to see on a 914 someday like a modern exotic car

Here's a vid if you haven't seen it.

http://www.youtube.com/watch?v=Y-Et-cJPgPM

That is a 300rwhp + motor blowing off 10 inch wide slicks.

The chassis is heavily reinforced and the car weighs around 1800 lbs......no dreaming here but the real thing driven in anger by a guy that knows his work.
300+ hp is not a part time thing. Purpose built is (IMO) the logical thing to do....unless you just want to brag about all that HP that you can't use.

The building of this beastie has been spread all over the net for the last 10 years......it's no small chore. If it were done by a shop the costs would more than double over the approx 35k invested.

BTW, it's still "nimble".....more so than most 914s.

The above re just my opinions. If you don't like them I have others.

On the Porsche-powered cars, the computer (DME or otherwise) makes it very drivable as long as you've chosen a clutch that modulates well. Carb's are another kettle of fish depending on the cam profiles and cold running as the Weber and PMO carbs don't have chokes.

And I agree with the idea that "buying someone else's dream" is far cheaper as long as they've done good work up to the point that you buy the car... I did.

Mine was a work in progress but I had a great PO and it came with lots of spares. That included a 2L six (T) along with the 2.7L engine that came in the car. I traded that for some 915 transaxles later on but with that and all of the other stuff it turned out to be a super deal. The PO already had about $25k in the car when I got it in '94 and I got it for less than 9k.

Good luck

I'd guess there isn't a whole bunch of money difference putting in a 3.6 (993) motor, along with a 915 as compared to a subi with 300hp.

And I'll bet there would be little if any performance difference, given the respective weights and all.

Don't know about the Suby torque, but the 993 works just fine with the 914 transaxle if it's properly built. And it's considerably lighter than the 915... and way cheaper. I have two 915's and one is ready to install, but the 914 transaxle simply won't break... unless I just want to do it for grins. Fortunately the 914 LSD will fit into my early 915 if I really want to install the thing. It's a spacer and shim adventure with the R&P at that point.

993 have torque everywhere and there is zero maintenance.

Glad to hear about the 901 holding up. How about the CV's, did you change them?

Ha, my stock ones only lasted 3 events and I only have a little 2.4.

Wow!
There is a lot of good info here.
I think I got my question answered in a round about way.

What I don't want is a point-and-shoot car. That was really the meat and potaters of the question.

I definitely don't want anything to do with a V8 in that car. Seems like 300-350 is a good number in that car for having the balance of being fast and still being able to handle it.

The youtube video was very cool, but like always is the case, you end up following a few links and next thing you know, the sun is coming up

Anyway, there is a very cool video (914 rally racing - or something) and the sound of the Porsche flat 6 is simply awesome. What kind of power can be had with a normally aspirated air cooled motor?

Lastly, whose ever car that is on this homepage has it exactly kitted out like I would want mine - very nice!

Cheers.

D

about to ruffle feathers here:

the 914 is old and has an old suspension design
the rear swing arm arrangement is not ideal
it makes a great vintage racer!!!!

most of the cars over 300hp (there are not too many) have gone to custom and even double a-arm suspension. The 914 is a great chassis, but it wasn't designed to support 500hp
by the time it is correctly built to do so (a full tube frame, double A-arm suspension, with a mendola transmission) it's hardly a 914 anylonger....

or you can build the engine and not really be competetive with a modern design except in a straight line.

I'm happy with a 2.0 so what do I know
brant

It is a slippery and expensive slope to head down. This stuff really is like crack. When you add significant power, you'll be grip limited. Improve the grip and you'll want aerodynamic aids. Do that, and you'll want more power. Oh yeah, then you need some serious brakes. And so on...

Good luck and keep us posted on what path you end up choosing.

I drive a stock 1.7 with D-jet every day. I've driven them with almost every 6 cylinder Porsche engine. I raced one with 150 HP for years. I've driven 4 V-8 cars, most recently one with 400-425 HP (new Corvette engine, I can't remember what HP he said.). The only thing in a 914 that I haven't driven is a suby or a turbo. In my experience so far, a 3.2 or a 3.6, slightly warmed over is probably perfect for very spirited street driving or on the track. That 400 HP V-8 car is a real hand full and you can feel the car flex. A 3.6 car feels as fast as a GT3RS. It will make you poop your pants a little but it's driveable. A 3.2 is almost as good. Neither one sounds as good as Donny's car with a 2.8 RSR engine but that's in a whole nother realm.
I'd rather drive my 1.7 around town than the V-8 cars any time.

The 914 cv's worked fine with both street and track use and I replaced them once after 10 years. I ran stock cv's both with the 2.7 and the 3.6, then changed to turbo (108mm) cv's on 911 axles for a couple of years.

Last year I finally converted to 100mm 944 cv's with a modified 914 axle and 911SC stub axles and output flanges. Now they weigh many pounds less than the 108mm parts and I can get 944 cv's all day long. That's because the 911 axles are too short for our 914's, require big spacers at the cv, and the turbo cv's are massive. But if you are going to use the 108mm gear you can either do what I did, buy SwayAway axles, or modify original 914-6 axles exactly like the 914-4 axle mod.
(The 108mm cv's have 911 splines as do the 914-6 axles)

Regardless of which system you go with, the key to longevity in both transaxles and cv's (everything for that matter) is smoothness in your driving style. Shift like a banshee and your stuff will wear out or break sooner. Be chronically smooth and your running gear will last a very long time.

Point is if I was building from scratch and was on a budget I'd stay with the 914 stuff. But since there is a 5-lug conversion in the cards anyway I'd go with the 100mm cv's regardless. The axles in that case can be modified 914's or SwayAway.

I went with the 944 CV's as well. Clean installation and they handle the torque of my engine, at least so far they do.

Good point about being smooth. That is always my objective, but sometime it's easy to get agressive, especially in an autox venue.

And as far as a 3.6 and more HP, that's easily done. Matt Lowrance will build you whatever you want, just remember that as you add HP you'll need to upgrade a bunch of stuff so that you don't end up with a car that isn't managable.

To be honest a 3.6 is a perfect all around engine. Tractable, very fast and low maintenance. It's tractable through out the RPM range, which allows it to be driven easily on the street, unlike a race motor.

And when you want to do a competition it'll take you some seat time to be able to use everything that is there.

My car was a V8

SCCA race car with a full cage. Full chassis stiffening kit, with extra stiffening. 930 Turbo suspension and brakes. 500hp axles, Tranny re-geared for higher rpm. Bilstein shocks all around.

The car is very stiff. Very little flex. I was able to push the car to the limit. There is a fine line between the cahassis limit and over power. My car was purpose built to go fast on the track. I'm lucky it's still street legal.

I decided to go far away from the norm on my build (see link in my sig). The problem with the V8 is having too much low end torque. The V8 can over power the chassis and loose traction. This can be dangerous if the car is not predictable. In my case the car is very predictable. The car settles into the corners the same way every time.

My new engine is a Turbo Rotary. 350hp @ 7000 rpm, 250 ft lbs at 4500 rpm (est.) the car is now 400 pounds lighter too. I expect the need to dial in the suspension again when I get it on the road. With my high gearing and an 8000 rpm red line, I should be able to hit 200 mph. The aerodynamics will prevent that speed though.

I did notice on my last inspection that I broke the front sway bar mount from the inner fender. The PO did a shitty job with the under tank bracket and it ripped the metal. Now I have something new to fix.

If money were no object, I would have gone with a 3.6 Porsche motor. But I have a history with the cute little Wankel. The are super light and makes tons of HP from a 1.3 liter engine.

Any engine swap you decide will be awesome. Even a hoped up 4 cyl can be lots of fun!



Just don't do this engine swap or you will get laughed at!

Click to view attachment

Didn't see that comin'

I've never driven a 3.6 powered 914 but i have driven a variocam 3.6 911, i can only imagine how nice that engine in a 914 would be, i think i would be the best of both worlds. If i build another that's the engine i think i would go with.

On the other hand a 3.3 turbo or like what i have a souped up 3.1 turbo engine is also a wonderful combination, very docile when off boost for city driving but hang on for your life when the boost kicks in, i feel like i have a well rounded street car going with the turbo, i dont have to worry about the torque load tearing things up in the low end
eventually the stress of the horsepower will take it's toll on drive train components on the high end but the car cant see much of that on the street or i will get in big trouble. I pick my spots to let it run but not something i can do everyday.

I don't even want to know how that all would work............

Hi David,

So much to consider! I've been running my 914 V8 with 500 HP (built 383) for some 8 years and have learned a lot in developing the car:

-Mine is a Track Car = Willow Springs Raceway, not a slalom car. If you plan to run slaloms, you will not be able to get your tires warm enough to put the BIG power down. I run 315/35-17 DOT Hoosier slicks and when I drive on the street, I can just light up the rear by opening the throttle in 1st, forgetting that I take a full lap on track to warm the tires and get traction.

-While you could tune a Subie up to 400 HP, you would be likely pushing the limit of the block. You can do it, but how long would it stay together? If you love rebuilding engines and have lots of $$, go for it! I'd suggest getting deeply into Subie forums to learn what can be done reliably.

-When you get big power (400 and up) You MUST have a full rollcage with tubing bracing all 4 suspension top load points. This gives you a RIGID Chassis. The original chassis is a true Flexy-Flier!

-It is important to STAY with a pancake engine to keep the CG low. The chassis
is designed around a low CG and low body roll. My V8 has caused me a lot of work in getting the car to handle due to the tall mass (I've posted extensive info on the roll vs. toe change of the rear suspension through the arc of travel).

-At 500 HP, the game completely changes:
-You MUST get a stronger trans. I have a 930, but Pantera ZF, Porsche 993 will work ($3000 - $8000), 911/930 half-shafts, 930 CV joints, LSD Differential, full bracing of inner and outer rear suspension mounting points and shift-linkage
-Then don't forget BIG brakes, dual-master cylinder + balance bar.

-Last issue is COST, I got 500 Chevy HP for $4500, I have no idea what that would cost in Subie.

So while I'm hoping to be helpful, I'm also hoping you are taking a step back to look at your plan before jumping in. I started my project with an Excel spreadsheet.

Best of luck,
Terry

Dr. Stein!

I was impressed by the car, but I was more impressed that you have so many immovable objects so near the course.

In SoCal at OCR events, we would be peeling 911's off of telephone poles about 10 minutes.

Impressive.

John

Wow!

Goregous car! Beautiful.

Very much similar what I have in mind except, I will do a cage, etc.

ARe you getting flow past your ic? I can't see what's happening on the bottom. How come you stayed with air to ari? I would think in a situation without much flow, air to water would be much, much better.
Typically the only draw back from air to water is latent heat and with a mid engine/front mount, you don't have that.

Either case, I'm sure your car is a hoot.


Cheers.

WSIR with a V8 914 would be a scary proposition...


What kind of times are you turning?

When I raced there with my S2000, we were at the 1:28 range on R compounds and 260hp....

I don't know what you must do there, 1:19?

Although I love the torque of a V8, I think that the 914 would benefit most from a high compression flat 6...

Some videos of the 914 GT, the sound and feel is just awesome..


D

500HP = "high compression flat 6"

Not a phrase that is very realistic... its possible, but not a good value and not easy.

I said high comp flat 6, not 500hp/high comp/flat 6

I agree, not very realistic.


As it is with track cars, sometimes driveability and response can be worth giving up 100+ hp.


D

My car is by no means a track car. These days, it's set up for street driving.

My engine was dynoed (is that a word?) at 305 HP at the flywheel. The car weights around 1900 lbs.

I think the combo would make for a very nice track car ...

That is certainly possible with forced-induction (turbocharging)...not easy or cheap

my bad
in the first post on the thread you were asking about 500hp 914's, thus the reason for my confusion.

Unfortunately we in the Portland area are not blessed with something like El Toro or even a reasonable faxsimility........yes, I'm jealous. Packwood big but 130+ miles away but is not as good from what I've seen of Mather or El Toro.
In my 10-12 years of ruining at the smallish venues up this way, I have seen about 3-4 contacts with immovable objects. Me thinks you are exaggerating a touch.

Granted, sometimes a newbie shows up in "flat out" mode and gets a stern talking to about safety. They settle down or are shown the door....but that should happen regardless of venue.

This is a piece of cake with a 500hp 914 at an autocross:
Click to view attachment

TTOD, not quite so easy.

I have two electric fans that pull air through the IC along with a fresh air duct on the spoiler.

POC has started using a large and fast parking lot course at the Pomona Fairplex here in SoCal - the highest-power guys probably hit 120+ and I was doing 110-115 on the long straights. There are definitely a few pucker spots with concrete barriers and poles, and it's also horribly bumpy in some places. However, with proper course layout and reasonably careful drivers nobody in our club saw a serious safety issue. They did move sections of the course farther away from immovable objects compared to the layout used for lower-speed groups such as the LA County Sheriff.

Click to view attachment

No worries.

I know I'm all over the place here and asking a million questions.

The funny thing is, I keep coming back to the same conclusion whether I troll here, go on youtube, or read other peoples' accounts.

This car has a sweet spot around 300hp. Seems that more than that, and it's no longer a 914. At that point, it becomes whatever engine with the 914 chassis bolted to it.

Another conclusion: If 300 really is the magic number, then for sure it's not worth putting a foreign engine in there. Too much custom fab and unknowns.

I think I might keep an eye open for a 2.4, 2.7 or even a 3.2 and staying air cooled

The 2.7s and the 3.0RSRs sound better than just about any engine I've heard before.

Hmmmm

Decisions..