anyone here ever compare a 2.8 High Comp MFI to a 3.6 vario?

[jmz]

Anyone here have experience driving each of these engines? If so what is the seat of the pants experience of each of these like.

Does the car like the lightweight mag case engine in the back better?

How about sheer acceleration and exhilaration?

I am wondering if putting the 2.8, marelli twin plug, MFI engine in the car might be in some ways more fun than a 3.6 conversion?


Thoughts???

[Steve@Rennsport]

Hi:

I've driven quite a few of these things,...

They have totally different personalities and performance characteristics. In a light car with close-ratio gears, a well-made 2.8 twin-plug motor is a VERY strong and potent car.

You've asked a great question and the answer is somewhat complex.

Each combo is very entertaining and offers greats fun; the 3.6 Varioram is a tire-shredding experience and the twin-plug, S-cammed 2.8 just screams from 4000 to 7300. The latter's soundtrack is worth all the efforts, IMHO and cannot be replicated by the 3.6.

Bottom line? Its all about power to weight ratio and having the proper gears. A good 2.8 in a light car with good gears is more than a match for a 3.6 V-ram and stock ratios.

[Walko]

Steve,

I agree with your views.

I think what JMZ was getting at was take the same car with the same weight and g/box ratios which one would be more fun.

Michael

[Jack Olsen]

I've driven both. My 3.6 is only a 964, but it has shortened gears and moves the car with much more authority than higher-hp, low-displacement, twin-plugged, high-compression motors I've driven (which cost many times what my 3.6 did).

Horsepower doesn't tell the whole story. You've got to look at the torque curves to see how the engine is going to feel as it accelerates, and how it's going to accelerate over the full rev range.

Granted, the early MFI powerplants sound much cooler and have more-chipper throttle response. They also look great. But horsepower-for-horsepower? For reliable, torquey performance, you can not beat big displacement.

The little motor will win the car show; the big motor will win the race.

[Steve@Rennsport]

Originally posted by Walko
Steve,

I agree with your views.

I think what JMZ was getting at was take the same car with the same weight and g/box ratios which one would be more fun.

Michael

Hi Michael:

I do understand what he was asking,.... Its simply one's opinion as what one would prefer.

As Jack said, there are many factors at work here and he kindly offered his opinion about what he likes and why; JMZ needs to get a ride in both iterations and make this intensely personal decision for himself.

A 3.6 powered car feels stronger due to the much bigger expanse of torque, however a side-by-side road or track comparison shows little difference. Both cars have their strengths and weaknesses. MFI/carbureted cars have throttle response that the single-throttle Motronic intake's cannot replicate, but there are many factors at work here.

Big engine'd cars are easier to drive but one should not make the mistake and underestimate a properly done, lightweight 2.8-powered car,....

Ultimately, its all about what each individual prefers and that simply must be decided for oneself.

[Walko]

Steve,

I hear what you are saying and I can agree that driving an early MFI is totally different to driving a 3.6.

I enjoy both. If i was only doing circuit racing then I would go for the 3.6 all day long however if i was doing tarnac rallying then I would be going for the 2.8 MFI

My two cents

Michael

[jmz]

All, Thanks for the info. Steve I wish I was closer to your shop to do some back to back comparisons with a properly set up small displacement/ big displacement cars.

What is it that seems to be so magical (maybe mythical) about the 2.8 litre engines? It seems that there is something special about these even compared to a 3.0 or a short stroke 3.2 set up in a similar fashion to a proper 2.8

Right now I am enjoying driving the car around with it's peppy little 3.0 but will eventually either toss my 2.8 after adding MFI etc. into my trusty steed or go with the flow and shoe-horn a 3.6 vario into the back. Either one is a pretty big under-taking and I would like to make the correct choice for me and maxamize the fun factor.

Cheers,

[Tinker]

What are you going to do with the car? Occasional weekend street toy or track time?

If you are planning on a street toy, then my vote would be for the 3.6. As mentioned, there's no replacement for displacement.....except maybe a nice twin turbo set up. They are reliable and relatively maintenance free.

But for me, my 3.6 on a track lacks that crispness or throttle response my old S cammed 2.7RS motor had.

As Steve indicated, on a fast track, I would bet a correct 2.8 would be more than a match for a 3.6.

Tinker

[RoninLB]

Originally posted by jmz

I would like to make the correct choice for me and maxamize the fun factor.

a 2.8 MFI is almost going to force you to have fun whether the PD likes it or not imo.

[Steve@Rennsport]

Originally posted by jmz
What is it that seems to be so magical (maybe mythical) about the 2.8 litre engines? It seems that there is something special about these even compared to a 3.0 or a short stroke 3.2 set up in a similar fashion to a proper 2.8.
Cheers,

The 2.8 is simply a great execution of all the basics:

1) Excellent bore to stroke ratio

2) Decent rod ratio (much better than 3.6's)

3) High compression (10.8:1 and above)

4) Great HP per lb (on a 7R case)

With good heads, cams, and intake/exhaust, a 2.8 makes excellent mid-range torque and HP/litre with a good RPM range. When coupled to a good close-ratio box, in a sub-2300 lb car, it really works well. Over the years, we've done several that make 250-265 HP (with S cams) in a 2100 lb car for a very quick ride.

If one is willing to stir the gearbox, and the WEVO stuff make that much easier, these are a lot of fun.

[rs911t]

a 2.8 MFI is almost going to force you to have fun whether the PD likes it or not imo.

I cannot drive my '72 with a 2.8S/MFI without laughing. The car is simply hoot to drive. Light, loud (sport muffler) and very quick. Throttle response is telepathic. Steve is absolutely right - the engine's personality changes noticably at ~4500.

The downside is fuel consumption. I run it rich due to the single plug and CR, and try to mix in a little race gas. Coupled with my inability to drive it conservatively and I see about 8mpg.

A sinfully fun car. No doubt I'm going to hell for driving this car.

[jmz]

Greg, How hard is it to keep the rear tires from breaking loose? It seems I recall your '72 is a narrow bodied car w/ standard width wheels.

[rs911t]

I'm not a burn the tires kinda guy. It is a nearly 35-year-old transmission. Easy enough to hang the rear end out, though. On the track with R tires the car sticks like glue.

[jmz]

I'm not a burn the tires kinda guy either. I am just trying to guage the amout of torque generated by the 2.8. Does your car have a LSD? My old 2.7 solex cammed motor used to break the inside rear wheel loose all the time (15x7) 225 in the corners at Auto-X. My 3.0 almost never breaks the the meaty 245's loose mounted on the 16x9's.

[jmz]

Originally posted by RoninLB
a 2.8 MFI is almost going to force you to have fun whether the PD likes it or not imo.

...OK, I give up. What does "PD" mean? Police Department???

[SalazarS2K]

Well, this thread almost describes my situation to a T. I recently performed this conversion from a 2.8 race motor to a 3.6 street motor and have been pleased with the results. However, my reasons for the transplant were to enjoy the streetabilitiy of the 3.6 vs. a high compression, twin plug, race motor on carbs.

IF I had planned on only doing track events and little to no street driving, I would have kept my 2.8 despite the race fuel issue. My 2.8 was mated to my 8:31 gearbox with custom gears and it was perfectly suited to the gear ratios with 7800 rpm topping out at 145 mph. The sound alone was worth it, let alone how nicely the car pulled in the upper revs. But, the 2.8 did not fit my goal as a street motor thus I sold to to perform the 3.6 conversion.

Just like Jack had mentioned, with the 3.6 installed in my 2200 lb. car, it just flat out pulls out of corners, no questions asked. With my current gear set, I can be in any gear and instant torque is right there, despite similar horsepower numbers from my 2.8. Too bad I can only top out at 128mph.

Practicality, and not peak power was my main reason in performing this conversion....oh, don't forget the FUN factor also. The 3.6 while not period correct, starts up everyday with no fuss, takes pump gas, is NOT highly stressed, and as a bonus, gets mid 20s mpg when you want it to.

[GrantG]

I wouldn't hesitate for a moment to choose the 2.8MFI. I love high revving responsive MFI motors in the light cars. I think the V-ram motor in my 993 is great (would be even better in a light car), but the MFI gets my vote. Jack is certainly correct about relative value though (well done mag motors with MFI are pricey!)

[mjshira]

I currently run a HC 2.5 engine. I have to agree with the 3.6 crowd. These are the same reasons I am going to a 3.6. I do enjoy the sound of the 2.5 but not messing with the points and other variables which will be DME managed in about... oh, I HOPE 6-8 weeks :-D

[jmz]

James, I understand about the points etc. I have a carb-ed 3.0 that runs good but I am tired of the smelly, persnickity carbs. If I go w/ my 2.8 then MFI and converting the marelli twin plug dizzy to ignitor points would be in order.

I wish I could keep the 2.8 for a later project, perhaps a proper 2.8 RSR replica but selling these bits would help to fund the 3.6 conversion tremendously. ...wife would be real happy with a budget neutral P-Car mod as would I.

JZ

[mjshira]

budget neutral???? has there ever been a budget neutral 911?? ;-)

good luck!

James