Ford GT dyno numbers are in !

shatner saves · Mar 13, 2004

So 300 hp on 87 octant sounds like a good deal, eh?

I would also think running 87 in those engines would do in a pinch, but if you ran it on a consistent basis, you might be looking at potential long term engine damage. All that spark retard generally isn't good for an engine. Even with the engine controls, you would still be risking knock if you happened to get an unusually bad tank of fuel.

awalbert88 · Mar 13, 2004

I get definate power degredation running 87 in my car (10.0:1 comp. ratio) vs running 93 or 94. Like a lot of other cars, it has a knock sensor and will retard timing. Audi specifically states in the manual that if you must run below 91 octane to stay out of the higher RPM range as you could damage the engine.

65conv50 · Mar 13, 2004

Z28x said:
LS1 = 10.1:1
LS6 = 10.5:1
LS2 = 10.9:1

They all run 91, the LS1 can even run fine on 87, although Chevrolet recommends 91 for peak performance.

What did GM change from LT-1 to LS-1 (other than aluminum block)? My LT-1 can't use 87 at all, struggles to get by on 91. Owner's manual says use 93, it will run on 91 but with power loss. I can do 91 OK if there is no alcohol in it, but it isn't really happy with less than 93. And it's a low-compression engine.

When the gas octane dropped (and it DID drop during the mid 70s - I was there - the "number change" is BS in my opinion) my Olds VistaCruiser with 11.4 (350 engine so-called highway cruiser) absolutely would not run on the cheap stuff that was labeled "Premium". I had to change the motor for a later 350 with lower compression ratio, about 9.0 if I remember correctly. I know fuel injection has helped since then, but it's no cure-all.

So I doubt some of the numbers being thrown around - from personal experience.

65conv50 · Mar 13, 2004

351CJ said:
C&D did a study on this a few years ago and did dyno runs. They tested 5 or 6 cars including a Mustang GT. They found that the cars designed to run on 87 octane had little or no improvement on 91 or even 93. But the cars designed to run on 91 octane showed a measurable loss in HP and mileage when run on 87.

It has been common knowledge for decades that you gain nothing from running higher octane gas than an engine is designed for, but can seriously damage it running significantly lower. Computer engine controls can help - within a limited range - with lower octane, because they retard timing when predetonation occurs.

65conv50 · Mar 13, 2004

While on the subject of numbers, I doubt some of the horsepower numbers being thrown around by the auto manufacturers. Example: my son's Chevy Monza with 5.0 (145 hp) was seriously faster than many "250 HP" cars on the road today. And it was even an automatic. And the "280 HP" Thunderbird is absolutely a snail in comparison.

351CJ · Mar 14, 2004

shatner saves said:
So 300 hp on 87 octant sounds like a good deal, eh?

Seems that a lot of people around here don't think so, but I do.

351CJ · Mar 14, 2004

65conv50 said:
It has been common knowledge for decades that you gain nothing from running higher octane gas than an engine is designed for, but can seriously damage it running significantly lower. Computer engine controls can help - within a limited range - with lower octane, because they retard timing when predetonation occurs.

It appears that many people don't know what others consider "common knowledge and others don't want to believe it, so it's worth repeating. The C&D article is also worth mentioning because it is a good, independent, unbiased direct comparison test that "proves" what many of us have known.

65conv50 · Mar 14, 2004

351CJ said:
It appears that many people don't know what others consider "common knowledge and others don't want to believe it, so it's worth repeating. The C&D article is also worth mentioning because it is a good, independent, unbiased direct comparison test that "proves" what many of us have known.

Good point, CJ.

Z28x · Mar 14, 2004

65conv50 said:
What did GM change from LT-1 to LS-1 (other than aluminum block)?

They changed everything. The LS1 is 100% different from the LT1

65conv50 · Mar 14, 2004

Z28x said:
They changed everything. The LS1 is 100% different from the LT1

Not quite. Both are 5.7 Litre (350 ci), pushrod V-8s with EFI. Same bore and stroke, same intake (aluminum), very similar electronics. No way it is 100%. Difference in power output is small. The difference is in the details, and that is what I was asking for.

JaysGreenLX · Mar 14, 2004

Those are some pretty good numbers

Z28x · Mar 14, 2004

65conv50 said:
Not quite. Both are 5.7 Litre (350 ci), pushrod V-8s with EFI. Same bore and stroke, same intake (aluminum), very similar electronics. No way it is 100%. Difference in power output is small. The difference is in the details, and that is what I was asking for.

They are both 5.7L but not the same displacement. LT1 = 350 ci, LS1 = 346 ci. LS1 intake is composite, Electronics are very different. I think they use the same oil fill cap, that is about it.

http://x.wieck.com/pv/WKA/2001/11/16/WKA2001111653891_pv.jpg

shatner saves · Mar 14, 2004

I wonder, If you took the new 3 valve 4.6 and bumped the comression to the point you would have to run it on 91:

What kind of compression ratio? 10.5:1? 11:1?

How much power, torque? 350+?

SadbutTrue · Mar 14, 2004

if you bumped compression to fully utilize 91 octane and 11:1 compression, that would put it at 325 or more (if its rated at 300 and thats correct and not underrated). Theres a general rule that i've seen that bumped the compression up a point, ie 10:1 to 11:1, will add up to 10% in terms of power. Obviously its a very general rule based on a lot of factors, but with 11:1 compression I think 325 would be expected, and 330-340 possible.

The LS series V8s also have far more aggressive stock cams than the 4.6Ls have had. Although OHC engines require less "camming" to produce the same effect as OHV, the LS series V8s have been "cammed" more aggressively even taking this difference into account. Somone posted about general NVH (noise vibration harmonics, i think) and they were far worse on the Fbodies, mainly due to this extra cam. On the old 2V engines, gains of 20 rwhp hp were common when people installed cams of similar aggressiveness to the LS1. This difference could be expected to be maintained in the 3V.

If Ford wanted to, they could change both of these with zero cost to themselves. A different grind cam or different piston cost basically nothing to ford, and the aforementioned two mods could be used to get the 4.6 3v to match the LS1 output and possibly exceeed it. Ford chooses not to because they realize the average person does not want/need 350 horses and tons of torque, they just want a fun car, which even the weak 96-98 GTs were able to deliver.

SadbutTrue · Mar 14, 2004

65conv50 said:
Not quite. Both are 5.7 Litre (350 ci), pushrod V-8s with EFI. Same bore and stroke, same intake (aluminum), very similar electronics. No way it is 100%. Difference in power output is small. The difference is in the details, and that is what I was asking for.

You need to do somehomework. The LT1 is nothing like the LS1. In addition to the differences z28 pointed out, the blocks basic construction are very different, with the LS1's resembling a SBF more than a SBC. The LS1 is only listed at 5.7L, its actually closer to 5.6, but Chevy bsed it a little to keep the line of 5.7Ls constant I think. And the difference in output is not small. By all accounts I've heard, the LT1 was rated pretty on the money at 275 hp. The LS1 is underrated and was probably worth 340-350 fwhp in every trim it was sold in, even when it was rated at 320 and such.

TheDamned · Mar 14, 2004

SadbutTrue said:
amazing numbers. so much for lutz's claim that a C6 z06 will stick with it, eh?

A C6 ZO6 will cost 10times less then that, don't compare this with vettes...

zykl0nb · Mar 14, 2004

TheDamned said:
A C6 ZO6 will cost 10times less then that, don't compare this with vettes...

So a Z06 is $15,000? Awesome!

shatner saves · Mar 14, 2004

SadbutTrue said:
if you bumped compression to fully utilize 91 octane and 11:1 compression, that would put it at 325 or more (if its rated at 300 and thats correct and not underrated). Theres a general rule that i've seen that bumped the compression up a point, ie 10:1 to 11:1, will add up to 10% in terms of power. Obviously its a very general rule based on a lot of factors, but with 11:1 compression I think 325 would be expected, and 330-340 possible.

The LS series V8s also have far more aggressive stock cams than the 4.6Ls have had. Although OHC engines require less "camming" to produce the same effect as OHV, the LS series V8s have been "cammed" more aggressively even taking this difference into account. Somone posted about general NVH (noise vibration harmonics, i think) and they were far worse on the Fbodies, mainly due to this extra cam. On the old 2V engines, gains of 20 rwhp hp were common when people installed cams of similar aggressiveness to the LS1. This difference could be expected to be maintained in the 3V.

If Ford wanted to, they could change both of these with zero cost to themselves. A different grind cam or different piston cost basically nothing to ford, and the aforementioned two mods could be used to get the 4.6 3v to match the LS1 output and possibly exceeed it. Ford chooses not to because they realize the average person does not want/need 350 horses and tons of torque, they just want a fun car, which even the weak 96-98 GTs were able to deliver.

"noise, vibration and harshness"

i4power · Mar 14, 2004

TheDamned said:
A C6 ZO6 will cost 10times less then that, don't compare this with vettes...

Yes, but Bob Lutz claimed the Z06 will hang with the GT.

Donny · Mar 14, 2004

zykl0nb said:
So a Z06 is $15,000? Awesome!

HAHAHA LOL!!!

I was thinking the same thing!!!!!

I still would pay that much for a POS Chevy!!!!!!

Donny

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