Hey guys I am trying to decide what to do so here's my setup:

Bone stock iron block 5.3 with 862 heads added a Texas speed 220r cam

Later put a lsa supercharger on it with a 2.45 upper pulley and stock ls1 lower crank damper/pulley. Theist netted me 547 rwhp 533 rwtq max of 14# of boost. So I "had" to see what else I could squeeze out of it so I put an ATI overdrive damper on it and it made 18# of boost. Of course the car had another problem unrelated and had to stop dyno and tuning efforts.

My tuner said I should put 317 heads on with arp studs and I saw most use ls9 gaskets.

Wanted to get advice and feedback.

 

Why did he recommend the heads? Is it detonating or something?

How fast are you spinning the blower? You may want to look at some intercooler upgrades to lower the IAT2's.

 

I would change the camshaft to something better suited for a supercharger.

 

^^^ This. Probably blowing a lot of your boost out the exhaust. With the right cam set up for a PD blower, you will likely see more with less blower speed...and that should produce less heat. Now I'm no expert but always have to remind myself that boost is a measure of back pressure and not necessarily an indicator of power. My experience with PD so far is mostly Cobras but it's a real mind f**k the first time you put big headers on and your boost reading drops significantly. Until that moment, everything you did increased the boost. Now I'm rambling; short version, IMO, 18# should be workable on 9.5:1 compression if everything else is ideal(93 octane).

 

A PD cam and better heads would work wonders. More power and lower IAT's all else being equal. I'd look at some used AFR 205's. I have the Mamo 220's(AFR casting) and they are fantastic but I don't think he's done with his small bore version yet. Plus they are $$$.

 

Yeah I can pick up his 317 heads on the cheap and have them put in pretty reasonable. I'll look into the AFR heads.

On the cam - I totally agree, I threw that one in there while motor was out of the car when I was running it before going insane on the blower trip... I would like to eventually swap that cam out but it will be a fair bitch with the motor in the car. Maybe i can do that a little later.

I have headers 1 7/8 primaries into 3 inch collector no cats and 2.5 mid to merge to 3in magnaflow exhaust and that's worked out ok so far.

He didn't seem concerened about detonation on the current setup, more concerned about lifting heads with 18# with it bone stock, no head bolts, etc... That's what lead into the conversation, and trying to make the best decision for the short term - 1 year...

Eventually I'd like to do a LQ4/9 6.0 build and replace the block, and leave the blower on there but with proper rectangular port heads, where I don't have to run adapter plates...

Another suggestion he made was back the crank pulley or the sc pulley down, to lessen boost and let it ride at 15# or less, but that's fairly costly as well, so its almost a catch 22, and hate not to get most bang for buck, and use the boost I'm making currently.

 

Is there a blower cam and head that you'd recommend?

Seems like 317 heads, ls9 cam, lsa cam, ls9 head gaskets, ARP studs/bolts are the consensus I've found so far.

 

Also intend on running pump 93 octane, with Methanol 50/50 injection.

 

Stock for stock, Your going to loose alot of compersion with a 317 head. 71cc vs a 61cc head...

I would either get the 862 heads re-worked or go to to an aftermarket head that you can reuse later on the next build.

There are several companies that will re work the 862 heads for you. I think Advanced induction even CNC's the chambers and can get them to whatever range you need them. I don't remember what all the companies offer, but look around. I would then spec the cam accordingly.

 

With meth you can get away with a bit more compression. Which 5.3L is it. Some had flat tops and others had dish. If they are dish the 317's would lower the compression a lot. Wouldn't be too bad if they were flat tops. AI can work over the heads for you but your in it for about $1k.

If those 862 heads came with the motor, you should be at about 9.5:1. I'd be perfectly happy with that. Just have the ports opened up as they are only 200/70cc. The biggest issue with them is the tiny intake valve.

Skip the LS9 cam unless you have a later model 5.3L with the one bolt cam and a X4cam/X58 reluctor. If it's three bolt and 1xcam/x24 reluctor have a cam ground for your needs. Kip, Martin, Ed, PatG and others will all be able to help you.

http://www.engpwrsys.com/index.php?a...od&productId=7

^is a good option.

http://www.advancedinduction.com/LSX...cGM706Head.php for the heads

 

2.00" intake has to work on a 5.3 bore..most gen IV 5.3s came with 243/799..2" factory. Easy/cheap way to make a 862 flow a little more is a 2" intake. Seat can even be cut to fit a 2" without actually changing the seat...and then you find some cheapie LS1 valves and you basically have a small-chamber 241/853 head.

Combustion chamber sizes:

862 - 61.15
243 64.45
241/853 - 66.67
317 - 71.06

Which brings us to a possible compromise: 241/853 have a larger chamber and larger intake valve already but not so cavernous as the 317. And cheap and plentiful. 243 heads demand a little more cash but flow even better and net you 3cc more chamber. I think for the boost you are running either is fine but the 241/853 would give you the ideal amount of headroom for a potential even swap(or close) on your 862s. While 243 heads flow better than 241/853, I think with boost the gap narrows a bit.

 

I would still mill the 241s down if you pick up a set. You don't want to drop compression too much.

I would still go the camshaft route before anything else. That is where a lot of your power is being lost.

 

Totally agreed on the cam. I think next is the intake valve. What do you think ideal combustion chamber is?

 

I was going to suggest something similar. More power with less boost. And also a cam with zero overlap or even slightly negative

 

I think dropping down to a Cometic .040 gasket to reduce quench and milling a set of 241s down to 64cc to keep the compression around 9.45:1 would be ideal. This is assuming an 8cc dish on the factory pistons and .006" above deck. I definitely wouldn't want to drop below 9:1, which is what the 317s and 241s would do in factory form. There isn't any need to go below 9:1. This isn't a Gen I motor with iron heads and an inefficient combustion chamber design.

 

^^ Yep. I hadn't put thought into the gasket but I actually wrote 64cc on the 241s and then erased it and posed my question. All left the same, it would be really interesting to see the difference in just the cam, then just the intake valve. But that's a lot of work. MAN I need my own dyno. I'd disappear for a year and only see daylight to harass the UPS delivery guy for parts.