Thread: N/A build up 10% cost 90% machine time

Good afternoon all! So I have been playing around with for a while but I think we need just a minute of background info:

Me: I am an ok mechanic, and a CNC Instructor for Lincoln Tech...I have access to machine whatever my heart desires, and if I can't put it together the auto mechanic side of the school can give me a hand.

My car: 99 Grand Prix with 151,000 miles. Repairs in the last year or so include: new fuel pump, fuel filter, tranny filter, map sensor, PVC valve, 180 thermostat, battery, spark plugs, spark plug wires, ignition module, coil pack (just one for now), lower radiator hose, other odds and ends I can't think of right now...biggest issue currently is leaking oil on to the manifolds...common in our cars, and the reason for this build...why replace when you can improve?

The goal: every project should have a goal and mines roughly 240 hp still N/A at the crank

So without further adieu here is the current plan:

-L26 heads machine port and polished
-L26 Upper and Lower Intake (to eliminate the plastic one) also machine port and polished as well as bore matched to an L67 throttle body
-Custom throttle body spacer to mount the L67 throttle body to the L26 Intake
-L36 Throttle body machine bored for more air flow
-90# Springs
-Rocker upgrade (looking at ZZP ER Rockers but would prefer to pull some higher ratio ones off another engine)
-ZZP front PLOG and down pipe
-custom aluminum version of the HV3
-CAI

what else can or should I do?

Cam it and put headers/downpipe on it. Then tune it. Also, that 180 stat isn't helping much since the fan turn on points are still 212-220. Probably killing some fuel mileage as the car is running colder. Then replace the valve cover gaskets and grommets to kill the oil leak.

Definitely do a cam over rockers. If you've got it that far, there's no reason not to. It seems you're pretty set on keeping it NA...headers and cam are about the only other things to do. Also, finding a thinner head gasket will bump up the compression and more if you mill the heads but you'll likely need new pushrods. You'll just have watch piston to valve clearance if you go with higher lift from a cam/rockers with thinner head gasket/milled head.

Agreed on the cam^ If you're going to take the time to work the heads and the upper and lower intake, you're only a few steps away from a full cam install. Just pull the lifters, harmonic balancer, front cover, and you're just about there.

The headers can be found used for less than you'll spend on the PLOG and downpipe too, but I'd personally only go headers if you cam it. From my experience the rockers do a little better with a PLOG and downpipe since they don't give you as many gains in the low end as a cam would.

You'll need a tune to run its best either way, with the cam you'll just have to add a CASE relearn.

And don't go with those 90# valve springs, they'll put more strain on your stock timing chain than they're worth. Some 105# LS-style springs would suit a mild cam or the rockers well since the spring rate is lower. If you go with the rockers you could even get away using some L76 springs, they're insanely cheap, have the same seat pressure as stock springs, and just a slightly higher spring rate. Not suited for a cam but with rockers they'll be even easier on your timing chain than the 105#. Just stay away from those 90#, the spring rate is just too high compared to what you really need.

I'm guessing you're going to fabricate the custom HV3 yourself? I'm not sure if aluminum (or metal for that matter) would be the best choice. The material that ZZP uses on the newer HV3's is some sort of very hard plastic (almost reminds me of polyurethane bushings), which allows a tiny bit of flex so you can pretty much press-fit it into the intake. You'd have to make sure the dimensions are perfect on the metal version or it would either fit loose or not fit at all.

Well as far as increasing compression goes I was only planning to face off .005" for a clean-up pass. From what I read .030" is max and if I'm going to have issues with pushrods I'd rather not up the compression too much. This is currently my only work vehicle and I don't want have to take my wife's tC over unless I have to. What would the compression ratio become if I were to go that route and what do you think the hypothetical horsepower increase would be from that added compression?

I had considered ZZP's GT1 cam, the GT2 mentioned issues with the torque converter and that's deeper than I'd like to get into it. ZZP estimates 30 hp with the GT1 which is great and I could have the Auto/Diesel class tackle that for me but it's more than I'd like to spend. Which is why I'd like to do rockers but I'd like to find if there were any that I could remove from another engine that would be close in ratio that may need a little milling to make it work.

As far as the custom HV3 goes I plan to make it a press fit...I'm used to press fits and tight tolerances so that isn't an issue...does it need to be a press fit? Just curious...

Im also a little nervous about getting headers bc I've read somewhere that the extra flow from them reduces back pressure to a point where it actually cause a drop in horsepower but I will def look into it...

Thanks for all the posts and the food for thought

Originally Posted by Turbocharged400sbc

small tube headers, qwik port the heads (find low core shift castings), tig weld rocker arm pushrod cups and relocate with 5/16ths ball mill to 1.9 ratio.

get an MLS gasket set, remove rivets, use only 3 layers, run .028 quench clearance by facing pistons to clay measures

a few oil and windage mods and id bet you could squeak 250hp but the fantastic part would be the Tq number...id bet the Tq curve would be pretty ****ing sweet even with the stock cams low/mid rpm bias. toss a nicer lobe at it and let it breath more than the smog cam and you have a helluva NA build

**** the hv3, bellmouth the LIM runners and leave the runner insert out with the gasket modified and sealing enhanced with a hair of rtv.

I retract my statement...listen to this guy. ^^^

Well now it sounds like me and you need to become good friends lol! I like your ideas and I'll look into tiging and milling the rocker arms...sounds like a good plan...I'm not sure about leaving out the HV3 wannabe as the lower intake manifold appears to have some pockets in it which would impede airflow and cause turbulence robbing some horsepower...I'm not looking to dig out the pistons either...I want to basically do an N/A top swap and not have to pull the motor out but thanks for the good advice! Keep it coming plz!

I'm having some difficulty finding information about what kind of filler rod would be best suited for the rockers as well as where I should mill to create a new ratio...I've never gotten this deep into engine redesign before so this is all new to me...can you find a link to a site with some info on this James?

Yes I'm familiar with pic-a-part and what's needed for a topswap but I shudder at the thought of premium gas and there's the kr issue as well...I actually like the thought of all that custom work...it's part of the appeal to say "I made this $&@!" Lol

Ive always wanted a no drama na build with a 100shot maybe more .
I was very impressed with the 300 hp 3.6 impala the last of the w body in a rental i had in feb.
Now since na builds take alot of work to make good hp and they are difficult to do i really want to see how this turns out!
I vouch custom grind cam and some compression by either milled heads the mls gasket mod or whatever and run it on corn!

I won't say money is no object because it always is (3 kids and 3 pets with one income)! Lol I like the idea of supercharging the L36 but it's been done (so has an N/A build though)...I guess my thing is I just want to push my creativity/machining skills and see what I can do...I've considered blue printing then modifying the current heads as I see fit from a raw billet but cost to gain ratio isn't great...cool factor yes, necessity no...I am considering making my own rockers now...I'm just working on my direction of the build and want some creative input from those who have been there before...

On another note I'm also looking into some custom carbon fiber body parts...I know a guy in town who used to make Indy car bodies but now makes a carbon fiber plane and said he would do some work for me...he does excellent work! I'm thinking bumpers, side skirts, hood, fenders, and doors too...but that'll be phase two of the build. Beast before beauty! Lol

Disagree 110% look at how light zach has got his gutted car and more weight off equals faster car and less hp required........

Front clip, doors, trunk, sideskirts, and rear bumper would be awesome the rest of the shell can meet mr sawzall!!!