930/964 turbo 3.3 vs 3.6?

[Beebop]

Briefly, what do the cognicenti consider as the "better" 964 series turbo? The 3.3 or the 3.6?

To give some context to this question ("better" is very subjective), I have a 3.3 upgraded to about 360-370 bhp (i.e. about the same as the 3.6), fitted with a Tial wastegate. When I test drove a 3.6, it "seemed" to have more mid range power / flexibility (but I have only ever driven one of each car). In general, should I find the 3.6 gives a better drive? Which engine is likely to give the least trouble over the coming years? Which engine has the greater power potential? Does the 3.6 have a significant petrol consumption advantage (official factory figures would suggest about 5-10% less fuel used and my upgraded 3.3 uses more in any case).

When I browse the various 911 forums on the web, I come across views that seem to fall into two camps: 1. 3.6 is the newer and [therefore] the better engine and 2. the 3.3 is a stronger, more reliable engine and has better upgrade possibilities. Reviews of the production 3.6 almost all seem to favour it over the production 3.3 (but then human nature is such that most would at the time, unless the 3.6 was a "pig in the poke" - which it certainly isn't).

Any comments from anyone who has owned and/or maintained both these cars?

 

[John_Ward]

As you rightly say, the question is very subjective. However, what is true is that the price premium paid for the RHD 3.6 Turbo 2 is a reflection of it's rarity rather than anything else.

 

[MegatronUK]

From what I've seen, you'll almost pay 993TT prices for a good 964 3.6 Turbo 2. I just couldn't bring myself to pay that kind of money, so went looking for a 3.3 Turbo 2 instead.

I understand that the 3.6 has better off boost pickup and fuel economy mainly because of the slightly higher compression ratio.

 

[turbo jonny]

I recommend doing some searches on the rennlist forums on this topic and/or buying Adrian Streathers book which lists the considerable number of changes from 3.3 to 3.6. I dont think it can be compared with the 993 as 4wd.

 

[911addict]

Beebop,
What other mods have you done to your 3.3 apart from the Tial?

 

[Beebop]

Sorry been away a couple of days.

Mark (911Addict),

Not a lot really, lots of maintenance but only the Tial wastegate. I have the rear box by-passed. The original wastegate was found to be in poor condition and I had the Tial fitted, as this seemed a much better and cost effective unit than the Porsche OEM one. I had the fuel injectors and fuel metering system overhauled; new coil, cap and rotor (but not leads as I couldn't source them anywhere in Europe or the US at the time [can now though]); various turbo related parts (by-pass valves and the like) renewed; lastly the fueling reset for the resulting setup. But that's about it. Why do you ask? I know getting the cat bypassed would be a good idea (probably most cost effective change, as mine is U/S and restricting the flow). I could also get a K&N filter (but I was advised it would make a little difference - of paper value, rather than driving value in practice (i.e. 5 bhp or thereabouts). Have you any particular further advise?
Iain.

 

[Beebop]

Hi MegatronUK,
That would accord with my impressions. Despite my upgrade, I find that I don't get that solid push in the back that I got from the 3.6. There's just a slight "unease" or "hesitancy" (to my mind) but it does only seem to be me that is aware of it. I don't know if that is particular to my 3.3 or a difference that would be seen between most 3.3 and 3.6 though. See my answer to 911Addict too tonight for what I have had done to the car. I didn't get the leads replaced (as I couldn't source them). I wonder if it's these. However, I have spent a lot of money to date with continuing improvements but never quite getting rid of this "unease". I'm loathe to keep spending money unless I have confidence that the problem is known. Even fitting leads on this car is expensive!! Obviously if it's an endemic "feature" then I should give up on it anyway.

 

[Beebop]

Hi Jonny boy,
I wasn't comparing with a 993 - but I wonder why you said that. Your comment could have "good" implications or "bad" or both. Clearly a 993 has many advantages and is a car I have thought about (not too seriously as yet - too expensive). But I have yet to drive one.

 

[turbo jonny]

I just meant that you can get either for similar price range but they are different animals and that should be the decision maker.

 

[911addict]

Hi Beebop,
I don't understand how your 3.3 can be making 360 bhp with just a Tial wastegate. Normally these cars are 320 (porsche conservative figures, so lets assume 330 for one that's running well).

About the hesitation and lack of push you mentioned. I have heard about hesitation (turbo lag?) on the forums and it seems that this is often due to a less than perfect operation. Most common seems to be failed diverter valve. Having gone from NA (normally aspirated) to turbo I have been amazed at both the lack of lag (except at low revs!) and the massive push from the turbo. Maybe yours needs checking out?

The only performance mods I have are the stainless steel heat exchangers (only a few extra HP but probably improved response) and the 100cell Cat (aka. Sport Cat aka. Race Cat) by Scart. This has been a very worthywhile improvement and the transformation at low end is amazing. It really does feel like a NA car and the delivery from 1000 to red line is smooth all the way, and I assume is more akin to a 3.6. These exhaust mods probably add around 20bhp so assuming mine is a well tuned standard car it totals around 350bhp.

The upgraded springs and wastegates I think will simply give you bigger boosts but will not alter the low end power delivery or lag at all.

With my current setup my car feels perfect (whereas before it felt unsatisfactory at low revs).

So to answer the original question, I have always said that a 3.6 is better but costs more. A 3.3 is great and can be made better with just a few "thou". Either way, a 965 is a special car, and without doubt one of the meanest looking!

 

[nathan 1981 930 G50]

ORIGINAL: Beebop

Briefly, what do the cognicenti consider as the "better" 964 series turbo? The 3.3 or the 3.6?

The answer to your question is the 3.6

The 3.3 is "better" value for money though.

Remember that the 3.6 will always be worth the extra money you paid for it compared to a 3.3 if you ever sell it.
In fact the 3.6 will increase in value more than the 3.3 might.

 

[Beebop]

Hi Mark (911Addict),

Oops you are correct - I did overlook one fundamental aspect. The Tial wastegate has a manual boost control in the engine compartment, with the boost currently set to about .85 bar. Hence the additional about 40 bhp. In my defence, it was past midnight when I replied and it has become (in my mind) inextricably linked with the Tial wastegate (since the two came together) and I overlooked mentioning it.
Iain.

 

[Beebop]

HI Nathan,

I see that you, like me, have a newer turbo but still keep an older Carerra. I assume you have the 3.2 (not the SC), as I do too. Out of interest why? I have to admit I bought the turbo with the full expectation that I would sell the 3.2 almost immediately. However, for some inexplicable reason, the 3.2 still involves me more than the turbo. Of course it's much lighter (1165Kg), which helps (IMHO). I'm just curious what you think of the two side by side on the UK roads so to speak.
Iain.
1991 964 Turbo [lhd], also fairly heavily modified
1983 932 standard coupe [lhd], as yet unmodified

 

[nathan 1981 930 G50]

My turbo is a '81 and therefore not as new as your 965.

I wanted to buy a '89 turbo with the G50/50 or a 965. I did find a 965 that appeared to be very very good but it was on ebay, I went and viewed but it wasn't long before the price shot up above my budget and also as it was not at a dealer he did not want my car in p/xchange.

I found my '81 turbo that has a G50/01 fitted at price that I did not need to sell my car to fund the 930 & once again it was not a dealer and there was no p/x option.

However it is a totally different car IMO, the 3.2 has a razor sharp throttle and the classic looks.
My 930 has a 964 3.RS look and gets a lot of negative attitude from just about anyone that sees it [] It is rather in your face and flash.
The 3.2 seems to get the majority of people smiling and being happy. It also seems a smaller car when you drive it and it does feel lighter although there is roughly only about 70KG between the two as I have had them both weighed. Maybe the narrower wheels and tyres do this as my 3.2 felt very different went I had some mille miglia 993 turbo twists on him.

The 930 weighed 1225KG with very little fuel in it. It will be lighter when I get all my tuning parts fitted.

Also another reason for not selling is that I would lose lots of money as I would never get back the money I have spent on him...

The turbo doesn't have those leather seats in it now, it has some Sparco Evo's.

The 3.2 is black, I had to brighten this picture as I took it when it was getting dark.



Also I think the extra boost pressure you are giving will only give about 25bhp. Are you checking the boost pressure with an aftermarket boost gauge or ebc & not the rev counter gauge ?

 

[911addict]

Nathan and Beebop,
I read somewhere that the 3.3 965 has a standard boost of around .8 anyway, although the gauge only goes up to .7.

Beebop, as I touched on earlier, your extra boost will give you increased and longer boost, but won't help at all with your response off boost. Much cheaper to address this than to buy a 3.6!

BTW Nathan, I had ignored the 930 which of course will be a totally different experience to the 965 anyway - nicer in some ways ;-)

 

[Beebop]

Mark (911Addict),

Yes you're right about the boost display - you need to fit another guage if you want to register above 0.7.

The Tial has improved boost at lower revs but not as low as 1000 RPM, 0.1-0.2 at best at 2000 RPM.

The "unease" as I call it, is not turbo lag - it is simply just an impression that the boost is somehow slightly uneven or "being throttled" by something or other (hence my question about the cat - see below). It is a subjective impression. Both specialists who have been involved in these upgrades have agreed it's there when I brought the car to them and both then said their fix got rid of it. But in both cases I agree they've much improved it but not (to my mind) totally eliminated it.

I know the one specialist has said the most likely cause is the leads - they're 10 years' old and on the upper limit of the factory resistance tolerance range. I know also that John Ward has said new leads was something he saw improvements from on his car.

You indicated that replacing the cat improved your low rev boost the most. Were your improvements done individually and hence you can say with reasonable certainty that it was the cat replacement that gave the biggest gain? Or was it (for example only) a case of improved breathing (e.g. you replaced the cats, the air filter etc)?

BTW, who sells the cat by-pass you had fitted? A google search for scart race cat failed to find a pertinent entry (at least in the first 50-odd entries of 652).

First it was fuel system, then most of the ignition, then turbo, then fueling again, .... Now it's a cat replacement that may make the difference or new leads that may make it. I'm sure there're other things that may make it too.

Hence why I asked the original question and why also the thread has drifted a bit away from that original question.

Cheers,
Iain.

 

[nathan 1981 930 G50]

Are you sure your issue is not the fuel mixture or the ignition timing ? Remember that the CIS is not as good as a full EFI.

Maybe you should also get a AFR gauge to confirm mixture settings as they differ on the road than on a dyno.

http://www.innovatemotorsports.com/products/MTS.php


Where to buy, a great company to deal with.

http://imagineauto.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=II&Product_Code=AFRGAUGE

 

[sjd]

My 1981 3.3 930 is highly modified - 475bhp on G-Force Rolling Road and likely to be circa 500bhp on the road on a cool day.

All I will pick up on is your concern re leads - I replaced mine as a matter of course earlier this year. Rather than go for braided version I used 8mm Magnecor leads. I sourced these from the US (ebay from recollection) and with postage and everything they were the right side of £200 all in.

Would I buy the 3.6 over the 3.3 - definitely. It is only a matter of money!!!

regards - Simon

 

[911addict]

Beebop (Iain)
Yes I can say its the cat that makes the difference, as its the only performance mod I have made to an otherwise standard 3.3.
I ran the car before for about 3 months and felt its boost was strong and smooth, just the off boost was a bit underwhelming. Did the cat and now it really is perfection, I kid you not!

The sound is subtly improved, nice growl and burble at low revs and quiet at speed. To give you an idea, here's a link to my vid: http://media.putfile.com/TurboScart2

Yes, the cat is by Scart, and their website is here: http://www.scart-exhausts.com/

 

[sawood12]

ORIGINAL: 911addict

Hi Beebop,
I don't understand how your 3.3 can be making 360 bhp with just a Tial wastegate. Normally these cars are 320 (porsche conservative figures, so lets assume 330 for one that's running well).

Just having a nose on this forum. My experience of Porsche OEM wastegates on the 944 is that they are pretty poor items. Don't know if this is the case just on 944's, as there is some speculation that Porsche used the wastegate on the 944 turbo to limit it's performance so it didn't step too much on the toes of the 911's of the day so the 911 turbo might not exhibit the same wastegate characteristics as the 944. However my 944 220bhp turbo was (or should have been) developing 220bhp off the production line back in 1987. As soon as I bought my car a few years ago I upgraded the wastegate (not a Tial but another dual port wastegate) and set the boost level to standard boost pressure (0.75 bar max) as I didn't initially upgrade the ECU chips to be able to take the extra boost into account for fuelling. On the Weltmiester rolling road (which is known to read low compared with other rolling roads around the country) I got 240bhp - so even a brand new OEM wastegate is bleeding around 20bhp through poor design and not being able to hold max boost pressure at higher revs - although you do get some pressure bleed on the 220bhp cars due to the turbo compressor capacity. The delivery of the boost is much better also - it comes in about 500rpm earlier and all in one lump so you do have to be careful when it does kick in but it is so much more of an exhilarating ride.

Now i've upgraded my ECU chips i've increased the boost level from stock 0.75bar to 1.05bar an it feels like a transformed car with turbo lag almost irradicated unless you are being really lazy with the gearbox - it drives almost like an N/A car in terms of power delivery with max boost still achived 500rpm earler than stock but instead of the square-faced boost delivery of the dual port wastegate with standard chips it is a nice smooth ramp starting well before max boost is achieved and my estimate of power is now around (hopefully over) the 270bhp mark (some have got 280bhp at Weltmiester with my setup). As I said I don't know if this is also the case with 911 turbo wastegates but it could be a worthwhile mod even if there is apparently nothing wrong with your stock wastegate. Also standard OEM wastegates cost about £1500 brand new (it's pointless buying 2nd hand as they are likely to be just as tired as the wastegate you're replacing) whereas something like the Tial wastegate is 'only' about £500 and is a much better and robust design. For those of you interested in modding your cars for extra power I would suggest your 1st port of call should be to replace your tired OEM single port wastegate and replace with a dual port wastegate.