Chevrolet Corvette Stingray C7 Forum - View Single Post

Rock36 · 08-14-2007, 06:45 AM

Some of my thoughts on the matter.

First Topic:

I'm not sure which 4.6L Mustangs that were being beaten with that straight six 4.8L engine from 1978. I don't see it being stronger than any of the smaller modular 4.6L V8 engines from 1996 to present even if it has more displacement. Take the new M3, that V8 is a paltry 4.0L and will destroy both engines.

I would imagine that straight six 4.8L from almost 30 years ago has heads that don't flow very well, a conservative cam, and is still carburated. Also, since it is the an engine from the late 70s it probably also has a really low compression ratio which also robs performance from the engine despite its larger displacement.

I couldn't actually find stats on the 4.8L engine mentioned (there was only a 4.1L that I can find) but the highest output from a 1978 Camaro was the LM1 5.7L engine that produced 185hp@4000 and 280ft-lbs of torque @ 2400 rpm. The 4.1 L inline 6 from that year only makes 110hp, so I would guess a 4.8L I6 would be somewhere between 110 and 185hp.

http://www.camarosource.ca/php/camar...pecs&year=1978

Secondly I'm support Dragon and I will back up some of his claims:

A 50% gain from a supercharger isn't unreasonable at. Many quote the "low" 400 bhp from this or that supercharger on the new S197 Mustang GT. Keep in mind those are the most conservative outputs of the superchargers for the current Mustang usually kept within limits to preserve the warranty.

Below is a link for a very safe 425 RWHP supercharger for the current Mustang GT followed by one for 450 RWHP. Both of these outputs at the flywheel would be near, at, or over 500 bhp.

http://www.teamjdm.com/shop/product_...roducts_id=212
http://www.teamjdm.com/shop/product_...roducts_id=213

Or here is another one from Kenne Bell. 401 RWHP on only 5 PSI of boost and on a non-intercooled set up. For an 8 PSI intercooled you have 445 RWHP.

http://www.kennebell.net/supercharge...gt05-06_3v.htm

The reality is that most supercharged Mustangs will be putting down well over 400 bhp usually they are over 400rwhp as I just showed, and as Dragon already mentioned.

About Superchargers in General:

Also roots and twin screw designs are also favored from the factories because of their low end torque production. Factory engines spend most of their operating lives below 3500rpm. Even at 3500rpm a centrifugal supercharger is just really starting to build power. The roots, on the other hand, is very responsive and the torque is immediate throughout the power band. So you can feel the torque when you are cruising around in 5th gear at 1900 rpm and decide to make a passing maneuver on a normal city street or freeway.

Final Point:

Many people prefer large displacement N/A engines over force induced smaller engines for many reasons, but in the end it is just preference and personal style.

It is true that in the end there is no replacement for displacement, but in the terms of practicality it doesn't matter. Unless you plan on building a 1000+ hp drag race monster, you don't really need massive displacement engines. You can be faster than 95% of street driven vehicles with just a turboed 2.5L from a mildly modified STi....if that is your thing....it isn't mine, but I am just making a point.

Yes I know I am talking about a Mustang on a Camaro forum, but the title of this thread is "Mustang prepares for its rivals"

Good day to all.

08-14-2007, 06:45 AM	#53
Rock36 I just like V8s Drives: 2007 Corvette Z06 Join Date: Mar 2007 Location: Stuttgart, Germany Posts: 919	Some of my thoughts on the matter. First Topic: I'm not sure which 4.6L Mustangs that were being beaten with that straight six 4.8L engine from 1978. I don't see it being stronger than any of the smaller modular 4.6L V8 engines from 1996 to present even if it has more displacement. Take the new M3, that V8 is a paltry 4.0L and will destroy both engines. I would imagine that straight six 4.8L from almost 30 years ago has heads that don't flow very well, a conservative cam, and is still carburated. Also, since it is the an engine from the late 70s it probably also has a really low compression ratio which also robs performance from the engine despite its larger displacement. I couldn't actually find stats on the 4.8L engine mentioned (there was only a 4.1L that I can find) but the highest output from a 1978 Camaro was the LM1 5.7L engine that produced 185hp@4000 and 280ft-lbs of torque @ 2400 rpm. The 4.1 L inline 6 from that year only makes 110hp, so I would guess a 4.8L I6 would be somewhere between 110 and 185hp. http://www.camarosource.ca/php/camar...pecs&year=1978 Secondly I'm support Dragon and I will back up some of his claims: A 50% gain from a supercharger isn't unreasonable at. Many quote the "low" 400 bhp from this or that supercharger on the new S197 Mustang GT. Keep in mind those are the most conservative outputs of the superchargers for the current Mustang usually kept within limits to preserve the warranty. Below is a link for a very safe 425 RWHP supercharger for the current Mustang GT followed by one for 450 RWHP. Both of these outputs at the flywheel would be near, at, or over 500 bhp. http://www.teamjdm.com/shop/product_...roducts_id=212 http://www.teamjdm.com/shop/product_...roducts_id=213 Or here is another one from Kenne Bell. 401 RWHP on only 5 PSI of boost and on a non-intercooled set up. For an 8 PSI intercooled you have 445 RWHP. http://www.kennebell.net/supercharge...gt05-06_3v.htm The reality is that most supercharged Mustangs will be putting down well over 400 bhp usually they are over 400rwhp as I just showed, and as Dragon already mentioned. About Superchargers in General: Also roots and twin screw designs are also favored from the factories because of their low end torque production. Factory engines spend most of their operating lives below 3500rpm. Even at 3500rpm a centrifugal supercharger is just really starting to build power. The roots, on the other hand, is very responsive and the torque is immediate throughout the power band. So you can feel the torque when you are cruising around in 5th gear at 1900 rpm and decide to make a passing maneuver on a normal city street or freeway. Final Point: Many people prefer large displacement N/A engines over force induced smaller engines for many reasons, but in the end it is just preference and personal style. It is true that in the end there is no replacement for displacement, but in the terms of practicality it doesn't matter. Unless you plan on building a 1000+ hp drag race monster, you don't really need massive displacement engines. You can be faster than 95% of street driven vehicles with just a turboed 2.5L from a mildly modified STi....if that is your thing....it isn't mine, but I am just making a point. Yes I know I am talking about a Mustang on a Camaro forum, but the title of this thread is "Mustang prepares for its rivals" Good day to all. Last edited by Rock36; 08-14-2007 at 08:50 AM.