gvs

Hi Everyone

Looking forward to improving my knowledge of the GM V8's. My fun car in a 1997 Jaguar XK8 with a 5.3 LS/T conversion its a a fun car!

regards

garry

Che70velle

iTrader: (6)

Welcome to LS1Tech Garry! Sounds like a fun car!

Hp-j

Nice sounds like a cool car for sure, any pics?

gvs

Hi guys


Would you mind giving me the benefit of your advice?

As you might remember I have a 97 Jaguar XK8 with the L59 vortec conversion. I don't have all the information on the conversion but I was told heads skimmed, aftermarket cam swap, custom exhaust and CAI, it has the drive by wire TB. I love driving it but have noticed that as i get more used to driving it and travelling further afield i seem to have a bit of a flat spot. Going up hill or nailing it the motor seems to bog down, the exhaust note gets a deep loud bellow for 2 or 3 seconds before the revs pick up and we are off again. So I am going through a bit of an intellectual exercise trying to work out what might be the problem! It loves travelling at 90 but not quite so much mid range?
The exhaust isn't blocked and the vacuum shows a drop off to near zero under acceleration and 23 on idle, there aren't any cats to become blocked, so I am assuming i am getting exhaust gasses out.
I thought it could be the stock stall converter on the 460 transmission and the gear ratio's, its a big drop from first to second so in dropping it falls out of the rev range, but, this also happens when rolling and the motor seems to linger in the higher gear before dropping down, if I nail it it seems to drop two gears and still bogs down for a second or two, but I am not sure if you have encountered issues with this before?
My next thought would be the correct fuel/air ratio and I wondered if the engine is being starved of fuel? Apparently the stock xk8 fuel pump is good for about 40 to 45 psi and my injectors are apparently the 36lb flex fuel type so I think those should be working fine, although i haven't changed the fuel filter yet. I then looked at the pictures of the other V8 motors on here and i noticed that my CAI is very long and as a consequence i only have a 4 inch by 5 1/4 inch air filter (its new) this gives approx according to Spectre around 500cfm, to get to over 600cfm i would have to move up to a 63/4 inch air filter either a K&N RU-5060 or a Spectre HPR 9617B ( not the 9615B I have) but I couldn't fit it because the CAI tube from the TB is so long, I think this was done to access the hole in the wheel arch where the original Jaguar air intake was.

I would have to cut it back 2 inches in order to move everything back to get the bigger air filter to fit.

I will take it off and clean the TBI and the MAF sensor but I am wondering about whether the car is breathing well enough out of the air filter set up, my filter is noticeably smaller than the other V8 motors you have on the gallery but i am not sure of the impact in cutting a couple of inches off of the CAI tube.
Any help and advice would be great the transmission is a L460E, both were out of a 2002 Tahoe. i didn't do the conversion myself, obviously so any help would be gratefully received. I have heard good things about Fuel Injection Specialties here in San Antonio so will probably end up there, unless nayone has a better idea?


cheers


Garry

Che70velle

iTrader: (6)

Garry, the LS series of engines require 58 to 60 lbs. of fuel pressure. That could be your issue, but before I jumped on the pump, I’d consult FIS there in San Antonio, and ask about a tune. Tell them your exact setup, including the pump. A quick street tune with a laptop connected will show exactly what’s going on.