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Jaguar Straight-6

 
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G@briel
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Joined: 23 Oct 2009
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PostPosted: Fri Oct 23, 2009 8:00 am    Post subject: Jaguar Straight-6 Reply with quote

Hi all, I'm new here Smile

I'm looking for some advice for modifying an engine that has next to no performance parts available and few people have ever heard of.

The engine I'm working on is a Jaguar AJ6 straight-6. 4 Liters, dual overhead cams, 24 valves, fuel injected, and all-aluminum. In its stock form it makes about 230 hp and 260 lb/ft of torque.

Several years later Jaguar came up with the AJ16, which was basically the exact same engine as I have (the only changes were the coil-on-plug ignition and a new fuel injection system, good for about 10 more hp). They also made a rare supercharged version of the AJ16, which was used in the Jaguar XJR and Astin Martin DB7. This one had more agressive cam profiles and the compression ratio was lowered from 9.5:1 to 7.5:1 through the use of different pistons. The supercharger itself was a version of the Eaton m90. It made about 320 hp and 385 lb/ft of torque.

It just so happens that I have an engine like this sitting in my yard, with one problem - it was overheated by the previous owner who was generous enough to let me have it for free. I was told that it had no compression on two cylinders and made a knocking sound but he didn't bother to investigate. Although the engine is probably not worth saving, the supercharger itself has its own oil and should theoretically be ok. However, when turning the supercharger pulley by hand there is almost an inch of slack in it from side to side - I have no idea what this means or how much is acceptable, if any.

Here is what I want to do - assuming that the supercharger from the fried engine can still be used. Take the supercharger and stick it on my older AJ6 engine, along with the newer camshafts, stock intercooler, then lower the CR somehow.

- The fully functioning supercharger originally made about 10-11 psi, what kind of CR is it safe to run with this kind of boost?

- Do you think the camshafts in the overheated engine would have been damaged?

- What do you think about the condition of the supercharger itself, can it be saved?

I also want to try and sort out the intake ports which are very badly aligned, as well as the exhaust manifolds which looks super-inefficient to my eye (see below), but I'll have to find someone who can make one from scratch. What size/shape of tubes would be preferrable? These are probably stupid questions...

I've included some photos of both engines bellow. The one with the black valve cover is the original AJ6, the silver colored one is the fried AJ16 engine.

Cheers Smile
Gabriel.

AJ6:









Supercharged AJ16:


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Knarley Darley
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Joined: 22 Apr 2004
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PostPosted: Fri Oct 23, 2009 12:52 pm    Post subject: Reply with quote

I just put 350 chevys in those with t-350 transmissions, and then they are pretty powerful.
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G@briel
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Joined: 23 Oct 2009
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PostPosted: Fri Oct 23, 2009 2:27 pm    Post subject: Reply with quote

Where I live I'll get ahold of a running supercharged AJ16 before I get a hold of a chevy 350, unless I pay big bucks for it. Besides, that would hardly be unique Smile
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10sec.et
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Joined: 29 Mar 2006
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Location: Houston,Texas
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1969 Oldsmobile Cutlass

PostPosted: Sat Oct 24, 2009 1:14 am    Post subject: Re: Jaguar Straight-6 Reply with quote

G@briel wrote:
Hi all, I'm new here Smile

- The fully functioning supercharger originally made about 10-11 psi, what kind of CR is it safe to run with this kind of boost?

- Do you think the camshafts in the overheated engine would have been damaged?

- What do you think about the condition of the supercharger itself, can it be saved?



-if you dont have anything for timing control, i would stay under 9:1. that of course is just an opinion. i dont really know what is involved in tuning that Jag.

-ive seen a LOT of overheated engines but never a damaged camshaft as a result. it would have to get stoopid hot to ruin the cam. ive had a few BMWs that got really hot with no camshaft issues.

-i would take the supercharger apart and inspect. from there you can decide if it needs a rebuild or is scrap metal.

oh, welcome to SMOKEmUP Cheers

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clay
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Location: South Carolina
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1972 Chevrolet Nova

PostPosted: Sat Oct 24, 2009 11:17 am    Post subject: Reply with quote

I don't think you could have hurt a cam either. On the supercharger, it might be a coupler failure. On the Grand Prix I had, it was a common problem for the coupler to develop some slop after some miles. Normally it would just cause a little rattle at idle, but wouldn't hurt anything. Maybe yours just came completely apart. If you want to put it on the higher compression engine, water injection would be your cheapest, easiest method to do it. I have run as much as 15 lbs. on a 9.8 - 1 iron headed SBC using it. It was intercooled, but I think you could do what you want using it. You could drop a little compression cheaply by shaving a little off the top of the pistions and doing some combustion chamber reworking. Usually a lot of heads are sort of shrowded around the valves, so by reworking these areas and cleaning up the entire chamber, you would be benefitting in two areas - slightly improved flow and lower compresssion. As for the exhaust manifold, you can get a ton of power out of a SBC with a 1 5/8" primary, so for your goals of low 300 h.p. or so, I would stay around that or you could go up to 1 3/4" if you wanted, but that's a large enough primary tube to make around 1000 supercharged h.p. on a SBC. The smaller primary might give you more clearance depending on what your bolt pattern is. Now tuning the fuel injection is completely up to you or somebody else with more knowledge in that area as I'm a blow through carb guy. I like unique stuff, so keep us updated on what you decide to do. Welcome to Smokemup. Clay
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I have done so much with so little for so long, I can now do anything with nothing.
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Mr.T
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Joined: 30 Oct 2008
Posts: 15
Location: Germany,Maryland &Wash.
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PostPosted: Sat Oct 24, 2009 6:43 pm    Post subject: Reply with quote

Jag,
I knew one fellow who used to raced the jag inline 6. The only way he could keep it together was to use a BB Chevy's huge Harmonic Balancer and keep the rpms below 6500.
Mr.T
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DeStroked
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Joined: 12 Mar 2010
Posts: 10
Location: Oregon
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PostPosted: Tue Mar 16, 2010 6:42 am    Post subject: Reply with quote

Did a little research and came up with a portion of a catalog that shows some nice exploded views of the AJ16 with correct part names and numbers. It's in PDF format. Here's the link:

http://www.xks.com/jaguar/catalog/pdf/jaguarcatvol15_113_146.pdf

This outfit, XKs Unlimited, is in Cali and specializes in Jag replacement parts, but Man!...sure do hope you've got some deep pockets! Here's the link:

https://www.xksunlimited.com/xks/merchant.ihtml?id=628&step=2

Best regards,

deStroked
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Big Dave
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Location: Tampa Florida
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PostPosted: Tue Mar 16, 2010 10:26 pm    Post subject: Reply with quote

I would just rebuild the toasted Jag motor. You most likely have a blown head gasket and unless it was run for some time that way the head can be shaved a bit and the block squared to put it back together again as good as new.

If that seems daunting you can run your current "high compression" motor with the compression you have by just changing the pulley size to reduce total overall boost.

The blown head may have the same casting number but it probably had bigger valves and some port work done at the factory (most Jags before Ford bought them out were low production volume hand made cars any way so a special limited edition motor was probably tweaked by the factory.) Most blown motors hold the exhaust valve open to blow a fresh charge into the cylinder and half way out the exhaust before closing the exhaust valve.
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