Oscypek

like the title states i don't know much about the 986. i know a bunch about the 944 and a lot more then that on 911's starting from the 993 but almost nothing one the 968, so i have a few?. are these easy to mod or not at all? i know the turbo s is extremely rare but is it possible to make a replica in anyway? basiclly what i was looking to do is get a junked up 968 and makeing it into a 400hp+ turbocharged monster and i just want to know if its even possible or if i should just get a 944 turbo (the styling of the 968 is just so much nicer). thanks in advance

flash968

oof - well, first off i'd make sure you didn't call it a 986 - lol - that's a boxster

a bit of searching at 968.net and 968forums.com will turn up quite a bit

400hp in a 968 is going to cost LOTS of money, and likely more than the purchase of the car itself - the 944 turbo will be a lot easier and cheaper

but, i'm with you - i like the 968 better

TheMirror

As an owner, I can tell you that mods to the engine in naturally aspirated form are pretty basic. Cat back exhaust from RSBarn or B&B, a chip from RSBarn or a couple of other sources, an airbox modification via 968engineering, and that's about it.......aside from a lightweight Fidanza flywheel. Past that, RS Barn can build you an engine with cams, headwork, etc., but these engines are pretty well maxed out from the factory. Even stock rebuilds on this engine are spendy. Much moreso than the single cam 944 engine.

http://www.rsbarn.com
http://www.968engineering.com

Doing a turbo conversion on the original 16 valve engine or retrofitting a 3.0L 8v turbo into one will cost you big big big bucks. It simply cannot be done cheaply with any reasonable quality. $15,000+ unless you are a master mechanic, or maybe slightly under $10000 with a used, stock 2.5 from a 944 Turbo....but what would be the point of that?

An increasingly popular engine upgrade for 968s is dropping in a Chevy LS-1 V-8 through Renegade Hybrids or one of the custom shops around the country.

Best,
-Mirror

whakiewes

My car may be your perfect candidate...you can see my forsale thread in the classifieds.

I don't agree that turbo'ing has to be a $15000 ordeal. I am 100% confident it doesn't have to be. It can be, but 99% of the turbo's I have looked at or seen are completely overbuilt for the factory. If you are a 1/3 competant welder, 1/8th competant machinest, and know a tuner, your taken care of. The problem starts with the lack of resources for a project...being that there may be 50 3L turbo's in the country, and 30 3L 16V turbo's, there isn't much of a market place for parts. Some of you may think I am nuts, but here is my agenda - Keep in mind that I am having some parts made, like a thick MLS headgasket which will also be available for sale. The turbo doesn't have to be a $1200 GT30R, or what not. The 3L engine flows plenty, and to say the least it should spool anything looking for 400hp with ease. So take a SC61, $850 retail. Good for 620hp. Maybe less than that go with an SC44 or GT3251, good for about 50lb/min, or 520hp. $700 for the turbo. You can be even cheaper and go the route of a used turbo, possibly a 60-1 for under $500 in good condition. So we'll say $700 for the turbo. OEM 951 cross over is going to cost $75, two piece is like $300 from LR. You COULD go big, but we are talking 400hp..so to me the SFR 2-piece headers are overkill until I see 1300+ EGT's. Two V-Band flanges for the cross over to weld onto OEM 968 headers, which are already on the car...$35. T3 flange for cross over, $50. Oil center/951 engine mount is a variable that is hard to find, but I would say I could get one for under $100. Tial 38mm (plenty for the 400hp goal) $300, maybe upgrade to an HKS standard 40mm at $450. I am will stick with the 38mm for 400hp. TurboXS H-34 bypass valve is 144.95, or if you wanted to go with the a Greddy type S or newer RS your looking at $200. I am going with the TurboXS. Intake manifold - here is where most guys will say your going to hike up your cost, but not to me. 968 manifold which I already have, cut about 2" away from the injectors, just past the nearly 90 degree bend. Aluminum intercooler end tank, or custom sheet aluminum...could really cut cost and go with sheet metal (proven in the DSM circles time and time again.). I am doing my welding myself, so I am looking at about $150 for the end tank, venturi's, vaccum ports, and flanges. Of course I could do something crazy like carbon fiber or something, but we are talking 400hp. Cometic MLS headgasket, 9.2:1 CR. ARP head studs to hold it together. Stock cams, variocam, cam gear, etc... 400hp again. Might go with upgraded springs/retainers and new lifters because of age, but thats speculative and on need basis. Tuning...well you could go two ways. I could sit around for several hours with my motronic tuner, play with mapping until its pretty darn close...99% sure with enough dyno time I could have it super driveable, 400hp atleast at the wheels. So with that said, I am going with an AEM Race box or the Haltech E11V2. AEM Racebox will be right around $600 through my vendor, the E11 will be 1100. Both come with flying lead harness, but AEM offers no support on the universal box...thats my dilemma. Doing the wiring myself, 3-bar map sensor is $150, GM water temp sensor is $35, and all my other sensors are compatible. Both run variocam fine. Both will have launch control, two-step, anti-lag, and more. $100/hr for dyno tuning, 4hrs is $400 with my tuner. So that leaves me injectors, boost controller, exhaust, and clutch. Again I am doing the fabrication myself, so I am playing with parts as we speak, but will be using a 951 based clutch, most likely Spec Stg. 3, on a 951 8lb flywheel. Clutch is $620 through my vendor, flywheel was given to me, machining is $50. 951 Torque tube is $100, bell housing was $75. Injectors, well tons of options. Supercheap would the Ford Motorsport 42lb'ers, which would handle 400hp on the 3L fine, 85% duty cycle with the AEM. Most likely though, I will go with Bosch 55lbs for now, so $300. The Ford parts are 1/2 the cost. Exhaust - $173.25 from Summit Racing, 3" aluminumized steel, 3" magnaflow muffler, 3" magnaflow race bullet muffler. Boost controller - completely end user choice. I want an electronic boost controller, but not something that requires more time tuning than the ECU. So most likely I will find a used Greddy Profec Spec B, early model. Good to like 26psi, gain feature, dual solenoid. $150 for that. Turbo timer isn't needed if you are careful, but we can say $75 for one. Man I almost forgot my intercooler. Front mount, Spearco core, reverse in/out end tanks, $475 at my door. Piping, $78.32 from Summit racing again. Silicone couplers will be about $100. So my misc costs would be nuts, bolts, argon, missed parts, broken parts, unexpected parts. I will budget in $500, but that is an expanding budget. So my grand total if you have followed in my exceptionally long and boring post - $4621 adding in a few dollars here and there, rounding up on everything. I would also like to add that my turbo wasn't as much as I quote, nor my waste gate, well nor anything. My total bill is just a hair over $2500. Nothing cheap, turbo was used but is currently being rebuilt. No OBX parts, all real genuine parts.

So I disagree that it has to be 'so' expensive. It can be, sure. But for 400hp it doesn't. I would also amend that my 968 rod is easily as beefy as my BMW S50 rod, and they are currently at a hair over 700whp at 30psi on a stock S50 rod. Its no 951 rod, but its lighter. Most dyno graphs I have seen of guys who bent rods, which was only two, were crap. The tuning either wasn't done, or was hacked. My car will sit on the dyno until its flat. I posted before, but I do plan on going big later. So I will keep tuning, and keep upping the power until I either blow my engine or can't go any bigger. I really expect an easy 500whp on a completely stock bottom end...but who knows . Anyone want to place bets....im in a betting mood! I also feel that someone has to take the initiative to do a DIY that works and comes out well, then it might turn into something more people enjoy.

Wes

saxman

I'd be a bit weary of dropping the compression ratio via a thicker headgasket. While it does work for that, you run into major issues with causing significant changes to the quench area of the head. Bad stuff.

I agree entirely though... I keep reading all over the place people saying $15000 for a turbo set up, that I find VERY hard to believe. Maybe to do an oem replica set up, but that's certainly not necessary.

Granted, I come from the turbo honda scene, where turboing high compression motors is normal buisness, and such, but it really seems to me that a lot of the 968 guys seem very afraid of boost. Even with an 11:1 comp ratio, 5-6 psi should be perfectly managable with stock internals with a conservative timing map. That probably won't get you 400hp, but it'll certainly make for good gains.


Out of curiosity, what's the need for all the work to the intake manifold?

Damian in NJ

There have been a million threads on turbo conversions-spend a few weeks surfing around here and you'll have a good baseline for further questions.

whakiewes

Sax,

The idea of quench area is on older ford and chevy V8's, they didn't have hemispherical combustion chambers...as don't 951's. When the quench area is raised, you get uneven burning, thus a bad combustion. The 968 has a perfectly round combustion chamber, as do BMW 6-cylinders, Supras, Skylines, etc... Its been practiced time and time again that the method of a thicker headgasket works. Again I will refer to the BMW scene - 2.8L, stock bottom end, 150k miles, cometic headgasket, turbo cams, porting, GT35R....600rwhp+.

So with that said, im going to play trial and error. There are tons of guys who want to turbo their 968/S2's, but are scared of the cost. Our engines aren't some special breed...they are a basic 4-cyl, 4-stroke, gasoline engine.

Wes

RajDatta

Wes, you do have it pretty much figured out. As stated, it is NOT necessary to lower compression by different pistons unless you plan to go over 400hp. A thicker head gasket will do the trick for upto atleast .5-.6 bar. This should give you a minimum of a 100hp increase if not more. Detonation should not be a big concern because of the pentroof head design as long as you intercool.
I am also considering going that route for the cabriolet. My budget for this would be in the $6-7.5K. I think it can be done. My biggest expense would be the intake manifold. I don't weld or claim to be a fabricator but do know where to source it all from. I plan to use 951 parts where needed as well.
I would caution on the light 951 flywheel though. The 3.0 has more harmonic issues as its a bigger motor. A lighter flywheel will give you some vibrations.
As far as it costing LOTS of money, its coming from people that have no 1st hand experience doing this on a 968. It will not exceed the cost of the 968 itself.
We can discuss this further offline if you are interested.
Raj

TheMirror

Sorry, I did a poor job of qualifying what I said there. I'm looking at it from a customer perspective, paying someone else to do the work.

Best,
-Mirror

RajDatta

Mirror, that was not meant for you but instead was a response to this statement,
Sorry, if I offended you in any way.
Regards.
Raj

flash968

there are some thigns missed here:

a factor not discussed is the requirement of a tight engine to do any of this - doing this to a used engine is a very bad idea, and will invariably result in failures, especially at those levels

this also does not address the necessary suspension and braking changes, and their costs

there is a very big difference between putting something together, and keeping that same something together - this seems to be ignored when talking about budget turbos

if you are doing everything yourself, and you value your time at zero, then i suppose you can complete the project for less - it has been done, though i have not heard of any of them running long or well yet

whakiewes

Raj,

Feel free to PM me. How about you let me blow my engine up first, then you can go from there . I have never done a turbo on a 968, so I can't say what I am going to do is going to be flawless. But I have done plenty of research, and its not that hard of the process. The 951 gives us a lot of useable parts, so I am going to use them. I have played with the idea of tuning the Motronic and saving a ton. I still may, and if I can't get anywhere, go with the AEM. The stock Motronic is very tunable, but not nearly as good as an AEM, MoTeC, etc... Maybe I can build my setup, make jigs, then when I am done build you one. I guarantee it will be way less than your budget, and 400whp. I already have the Cometics in processing, so thats taken care of. Exhaust is made, cross over pipe is here, working on picking up the torque tube/bell housing, so its in the process. Turbo is being rebuilt. So pretty much I just need to spend the time designing the intake manifold. PM and I can give you more skinnies on the project.

Wes

whakiewes

Raj,

Feel free to PM me. How about you let me blow my engine up first, then you can go from there . I have never done a turbo on a 968, so I can't say what I am going to do is going to be flawless. But I have done plenty of research, and its not that hard of the process. The 951 gives us a lot of useable parts, so I am going to use them. I have played with the idea of tuning the Motronic and saving a ton. I still may, and if I can't get anywhere, go with the AEM. The stock Motronic is very tunable, but not nearly as good as an AEM, MoTeC, etc... Maybe I can build my setup, make jigs, then when I am done build you one. I guarantee it will be way less than your budget, and 400whp. I already have the Cometics in processing, so thats taken care of. Exhaust is made, cross over pipe is here, working on picking up the torque tube/bell housing, so its in the process. Turbo is being rebuilt. So pretty much I just need to spend the time designing the intake manifold. PM and I can give you more skinnies on the project.

Wes

flash968

fun project nonetheless - going in with the expectation of problems and complications goes a long way toward mitigating the beer expense

keep us in the loop

whakiewes

Ohh, the beer fund is endless... I just don't want it to turn into a project where I need a liquor fund as well . Been down that road with an Audi Coupe Quattro.

Wes