again nice find xjsv12; yes with less weight you would need less spring rate.

could also help with available parts bin(cost).

 

Doh I'm stupid sometimes I have a 5.3L HE in the shed, I'll pull a set of valves out and measure the valve spring rate.

 

.

good idea warrjon, also measure spring free length and spring diameter?

 

I went to flow the spare 5.3L head I have which has no studs in the head so I pulled a stud from my 6.0L head, needed to hold the valve opener.

Gotta Love Jaguar/Ford, the cam carrier studs in the 6.0L are M8 and in the 5.3L 5/16UNC

 

The new Exh valves are square on the margin where the originals have a very generous radius.

Original valve


New Valve


New valve modified

 

it may help exhaust flow get started into port!

also eliminate a potential hot spot.donno.

who made the valves , any possibility of actual material?

 

Don't know who made the valves, Norm sourced them

 

The main supplier was AE. They were pistons, rings, valves, valve guides, chain. Vandervell made shell bearings. Then the TRW produced guides and valves.
AE made replacement STD and oversize shell bearings

 

did you get to flow test the 5.3 heads?

 

No because the head stud thread was UNC and the 6.0L is metric and I didn't have UNC studs to mount the valve opener to so I could not flow it.

 

Just FYI, in case you hadn't noticed, Mark Eaton on Jag-Lovers did some CFD modeling of the various V12 ports coming up with some interesting numbers and simulations.

https://forums.jag-lovers.com/t/engi...nt-inlet-ports


Paul Kobres

 

Thanks Paul, I have read that thread.

I'm lucky as I have Norm helping me build my engine. The engine is being built for torque not peak HP and will be using stock valve train, I built my own flow bench and have optimised the port for the valve train.

I have a head on my shed floor Norm loaned me which is off a 6.0L V12 out of a Hydroplane and made 615hp, the ports on this engine are small (about 35mm) with very large intake valve.

 

Unfortunately All the pics I had in most threads were hosted on PhotoBucket, PB's decision to now charge $400USD a year for this service made ALL photos past no longer available to view. So I have deleted my PB account

 

Yeah.. I was opening each pick in a new tab, then reloading the main forum page which allowed all of them to properly load. Any chance you might find time to upload them to a different site and edit your posts so that the pics might be available for posterity? I'm looking forward to hearing how the engine performs, you've cut the ports in a way that I suggested on Jag-Lovers many years ago and I'm very hopeful that you get great results from reshaping that seemed instinctual to me.

I agree, a *sporty* XJS driver doesn't need more than the high 300 to mid-high 400 HP range.

Paul Kobres

 

Unfortunately I can not edit old posts to update the pics. Oh well

I am lucky to have Norman Lutz building my engine, from the simulation he gave me I should have around 400-450hp.

I drove my brothers Mustang GT500 before it was detuned as it had too much power for registration around 700hp, it was difficult to drive, even now with around 550hp it's still a handful especially in the wet.

My plan is to re-install the 2.88 diff to aid in traction, the simulation/experience I should have around 500ftlb's

 

Warren how's your engine coming along?

I think but maybe imagining that you mentioned a centrifugal supercharger somewhere on this forum. Why did you not choose that route?

Also if you are using a later 6L engine are you bound by stricter emission requirements?

I hope don't mind the questions. John.

 

No don't mind the questions at all.

I'm taking the heads to Norm on Saturday, I've decided to use the head guy he uses. When they're done I'll pick them up and CC the chambers. BTW it's a 3hr dive each way.

I was originally looking at supercharging, but the government changed the goal posts and FI on an engine over 3.0L requires a lot of engineering (read huge expense) unless the model had the engine as an option. My brother has a 1967 Shelby GT500 (genuine) he rest-modded it with rack and pinion steering and coil overs, all supplied by Shelby including the engine rebuild of around 700hp, it cost him nearly $30,000 to have the car engineered. He had to rent a race track for the engineer to do brake testing.

The 6.7L will have a lot of torque estimate around 500ftlb's and around 400hp, more than enough for a spirited fang around the back roads near where I live.

 

New exhaust valves

Left is the original valve, Middle is the new valve and right is my modified valve with radius on margin

 

Warren thanks for the response. Looking at VSB14 the "recommended" max engine capacity is 3 x the manufacturers weight in kg. So 3 x 1825 = 5475cc which should make a supercharged 5.3 ok. In theory anyhow and possibly NA maybe a better option when looking for reasonable outputs.

How are emissions handled on a modified engine? Are the standards you need to meet based on the age of the car or engine?

I'm looking forward to see your results.

 

In VSB14 any modification that increases power more than 20% must be approved by a VASS signatory, this is where it gets expensive, I'll be registering my car as a 6.0L which was optional in 1989.

The car has to meet emission standards for the year it was complianced here so 1990 for me. But we do not have annual Road worthy inspections in the state I live and emission testing is not part of a RW even if needed.