LPG and V8 Mods

amiers · 16-09-2006, 09:42 AM

i know there is a LPG forum but i wanted to get a general opinion from the main forum. how far can i go with mods to my fairlane without stuffing around with the gas. iwant to leave the gas standard but want to drag some more KW's out. i have done a bit with the air box, k&n filter, larger intake. i am thinking extractors and full duel system, secondary cold air inlet. what else will be ok with the gas?

JC · 16-09-2006, 08:08 PM

Quote:

Originally Posted by amiers

i know there is a LPG forum but i wanted to get a general opinion from the main forum. how far can i go with mods to my fairlane without stuffing around with the gas. iwant to leave the gas standard but want to drag some more KW's out. i have done a bit with the air box, k&n filter, larger intake. i am thinking extractors and full duel system, secondary cold air inlet. what else will be ok with the gas?

I have Herrod/DeFillipo 4into1 extractors, plus single 3" exhaust, plus I have 1.72 ratio roller rockers (ST2027s), and BA pod with custom 3" stainless inlet pipe. All up this gives me 138rwkw on LPG and 144 on petrol. Best prior to gas install was 149 on petrol (different dyno though), so I reckon the 138 is great. Especially when compared to around 125rwkw standard (mine's auto).

All the usual mods work with gas - the only caution I would offer is if you have a balance pipe setup, you can have only ONE air intake into the box/BA Pod/whatever. The balance pipe needs to sit in the airflow going into the filter, so you cannot use a supplementary intake. i have the BA Pod, plus I use the tickfors snorkel and some 3" ducting pipe to direct air down to the front of the Pod intake - it's not actually joined, It just flows cold air down to the front of the BA intake, which draws air from behind the headlights.

BPXR6T · 16-09-2006, 09:42 PM

You can bump up your compression ratio with gas can't you. If I had a windsor again I'd stroke it, stick a good set of alloy heads on it, get a decent manifold, and a good cam. Stroking is relavtively expensive but assembled alloy heads can be had cheap and a cam install is pretty easy.

Abacus · 16-09-2006, 10:41 PM

Hey JC, what have you got from the cats back? Are you IRS?

JC · 17-09-2006, 12:29 AM

Quote:

Originally Posted by Abacus

Hey JC, what have you got from the cats back? Are you IRS?

Yep, IRS. From cats back are twin 2.5" that go into single 3" around about the point behind the drivers seat. Then 3" over/under the diff. And Yes, it's IRS. Sinlge 3" (apparently better for torque) or twin 2 1/4 is the way to go - twin 2.5" for higher power applications (160rwkw+).

Abacus · 17-09-2006, 02:49 AM

Quote:

Originally Posted by JC

Yep, IRS. From cats back are twin 2.5" that go into single 3" around about the point behind the drivers seat. Then 3" over/under the diff. And Yes, it's IRS. Sinlge 3" (apparently better for torque) or twin 2 1/4 is the way to go - twin 2.5" for higher power applications (160rwkw+).

Thanks JC. What did you do with mufflers - did you find you needed a resonator?

Oh Amiers, sorry if I seem to be hijacking the thread - I'm trying to contribute to it. My 5.0L is also getting a Parnell VSI LPG install, and I'm trying to get the performance stuff done first so that they can install the LPG system around the exhaust and other work, rather than the other way around.

Every exhaust shop I go to seems to have different ideas. I'm after torque, not outright HP, so I'm putting on tri-ys (Pacemaker 4001s). Some places say I should go 2.5" because there won't be enough back-pressure with 3", others say 3" is fine. Some say 3" is bloody loud, others say that they can make it sensible. Some places say I have to add hi-flo cats, others say the standard ones flow fine. Some places guarantee the system won't resonate and vibrate through the car, others won't. And so it goes on. Its driving me nuts.

If it's any help to you Amiers, I've already put on a Tickford intake and K&N. There may be a slight improvement from that, but I don't know if I'm imagining it. I gather, from other threads, that the improvement is gradual as the ECU gets used to it. If that is the case, it may well be an improvement, but because of the gradual nature of the improvement I haven't noticed. The car definitely sounds better.

I intend to sticking in this cam, Crane Came p/n 444225, formerly known as the 2031.

http://www.cranecams.com/?show=brows...tNumber=444225

There is a slightly harder cam called the 2030, but I gather there isn't all that much difference and you need to change the rocker ratio from 1.7 to 1.6, and it wasn't what I was after.

If I had known what I know now I would have bought this kit, which includes the cam and upgraded valve springs, because it's cheaper to do it this way than buy upgraded valve springs separately.

http://www.cranecams.com/index.php?s...26&lvl=2&prt=5

I have been told I ought to put in roller rockers, but seeing as I'm after low-mid range torque, not top end HP, im not sure that these are necessary. Roller rockers that work with that cam are Yella Terra roller rocker ST2027 (1.72 ratio)

You may also need longer pushrods (definitely will if you put in the r/rs) and its a good idea to put in a new timing chain kit while you are at it. After you've bought all that, you may as well buy a new set of lifters as well. I haven't bought these yet, so I can't help with part numbers. If you want to buy all Crane stuff, this page helps:

http://www.cranecams.com/pdf/Page430-439.pdf

I am informed that LPG will be fine with all that stuff. Other, more knowledgable, members should be able to confirm this.

The one thing I haven't looked into in any great detail is the chip options, basically because thinking about it makes my head hurt, and every time I start to think about it I decide I would rather have a beer.

I am told the standard ECU is pretty smart when it comes to working out what to do with all this stuff. Having spent, or committed to spend, so much on an LPG installation, extractors, exhaust, intake, cam, and installation of these items, I would prefer to defer the additional $1,500 or so for a chip. You may have different ideas. Again other, more knowledgable, members will help you out with advice in this regard.

Hope the above helps.

amiers · 17-09-2006, 07:21 AM

JC, when you say balance pipe are you refering to the curved pipe half way up the air intake pipe? it bolts to the shock tower.

JC · 17-09-2006, 01:35 PM

Abacus - my system is loud. I have one straight through muffler before the diff, no resonator, no hot-dog, no rear muffler. I'm pretty sure mine is legal, and it doesn't really drone (it does at 60 and 90, so I just avoid those speeds). Good advice on all the performance parts. One question I have for you - are you sure you need to change the pushrods when fitting the 1.72 RRs? I didn't, and I wasn't advised to either - in fact I was told I wouldn't need to (by the bloke at Repco).

Amiers - the balance pipe is part of the LPG setup. Not all systems have it, but the landi renzo does. Here's a pic of a balance pipe fitted to the intake par of the CAI - borrowed this pic from GK!

Abacus · 17-09-2006, 01:50 PM

Quote:

Originally Posted by JC

are you sure you need to change the pushrods when fitting the 1.72 RRs? I didn't, and I wasn't advised to either - in fact I was told I wouldn't need to (by the bloke at Repco).

That was the advice I was given on this forum. Your experience clearly proves me wrong. :Reverend:

Are you running a 2031/ST2027 combo?

JC · 17-09-2006, 01:57 PM

Quote:

Originally Posted by Abacus

That was the advice I was given on this forum. Your experience clearly proves me wrong. :Reverend:

Are you running a 2031/ST2027 combo?

That may be the difference - I'm running stock cam with the ST2027s.

amiers · 17-09-2006, 02:58 PM

thanks jc, i do have one