Vantage V8 4.7 engine rebuild
#76
2 totally different engine purposes and build goals. Road going engines are made to last longer in stop and go and highway lower rmp usage, their tolerances reflect that.
Race engines are measured by hours of useage, their tolerances and materials reflect that. They are very strong if they are Endurance racing motors, the opposite end from fragile and delicate...I wouldn't call being at redline almost all the time over 24 hrs of uptime "babying" a motor at all. That's why they get rebuilt periodically based on hour logs, stuff wears out, they are under severe conditions and the highest usage load possible.
Race engines are measured by hours of useage, their tolerances and materials reflect that. They are very strong if they are Endurance racing motors, the opposite end from fragile and delicate...I wouldn't call being at redline almost all the time over 24 hrs of uptime "babying" a motor at all. That's why they get rebuilt periodically based on hour logs, stuff wears out, they are under severe conditions and the highest usage load possible.
Oh, I hear you. I just thought it was noteworthy that a guy from motorsport likes to remind people that the engineering for DDs is actually impressive in it's own way.
When he talked about the "babying" he referred to the gentle warming of the engine with external heaters, the frequent tear down, etc. Yes, of course these things are the nature of the beast. All respect to the awesome that is an F1 (or any racing) engine, but I'd rather not have one in my DD.
#77
I was disappointed when I saw the rods and pistons. However the motor is well balanced which bodes well for longevity. I have had some experience with race engines, albeit the push rod variety. Wear was main issue, catastrophic failures were usually brought on by greed for horsepower or ancillary failure.
#78
![Wink](https://www.6speedonline.com/forums/images/smilies/wink.gif)
#79
Ibis and Sunir,
Someone (Colin Chapman?) said that if a race engine can last one lap beyond the end of the race, then it was overbuilt...
The different and severe demands of race engines and street engines are why street car engines that are able to serve as the base for "production-based" endurance racing engines appeal to me; they have to be able to withstand the demands (many of them, anyway) of both the road and endurance racing.
Someone (Colin Chapman?) said that if a race engine can last one lap beyond the end of the race, then it was overbuilt...
The different and severe demands of race engines and street engines are why street car engines that are able to serve as the base for "production-based" endurance racing engines appeal to me; they have to be able to withstand the demands (many of them, anyway) of both the road and endurance racing.
#80
Jag 4.2 rods
What a great post you did on the AM engine rebuild! I found it doing a Google search to look for what kind of rods are in my car's engine. You seem to be the kind of engine tech that I may want to hire next year to begin the build-up of my next motor.
Here's the short version of what I've done to my car, leaving out unrelated info like transmission, differential and suspension mods, etc.:
Model Year 2000 Jaguar XKR convertible (originally 4.0) now with a 2003 4.2 AJ34S engine (44,000 miles). The Eaton supercharger has been replaced with a Kenne Bell 2.6L twin screw supercharger, 90 mm custom throttle body, custom mapped MAF and 3.5" intake to behind the front bumper. Water/methanol 50/50 (I mix it) injection comes on with a strong dose at 11 psi. 21 psi is the max. The engine retains the stock 6200 RPM limit. The factory engine has a forged crank. It seems to me, after seeing your photo and reading your commentary, that the rods are a weak point.
The creator of the custom supercharger kit has had it on the same set-up in his Jag for over 100,000 miles of daily driving. His car has been regularly tested on a dyno. Latest dyno 524 rwhp (631 HP). His engine does NOT have water/meth injection like mine does. His car also retains the standard 6200 RPM limit. I have not had a dyno run with my car yet, but I assume that my engine develops slightly more horsepower if compensated for the same temperature and elevation, etc.
I am considering using a slightly smaller pulley, going from 3" to 2 3/4" and feel that I can get away with it since another Jag owner has done it (same engine/supercharger install) without having the motor go POOF, yet. His car is also a daily driver like mine and the other guys with this same mod. I believe that his psi maxes at 25psi. Some of the higher performance Jag guys (that don't have the Kenne Bell upgrade) like to raise the RPM limit to 7000 to get more power. It seems to me that it would be safer to leave the RPM limit at the factory level. Thoughts?
Next Spring, I am going to purchase another 4.2, just like I have now, and have it rebuilt to the kind of quality that you provide. I'd like to have it built up 'correctly' like you do, with the right kind of internals for performance. My Jaguar technicians are fantastic, but they specialize in restoring Jags. They can do a GREAT engine build for me, but it would be more like a high quality factory motor. I figure that it would cost around $15k or so, based upon your commentary.
There are 5 or 6 of us older Jaguar XKR owners in the US that have this Kenne Bell supercharger upgrade. So far, no one has had any problems.
I can be reached at: monsoon (aaaat) comcast (dawwwwt) net
This is the toy. It's had a lot done to it since the photo, such as lowered, new OS Giken 1.5 differential and huge brake kit, and it sure does scoot!
#86
Sure, but the thread starter isn't an owner, but rather the person whom seems to have done a phenomenal job of rebuilding a 4.7 for an owner.
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11-22-2010 10:45 PM