86 GT Winter Changes

[rock4451]

Hey guys,

Haven't posted in a while and since I know this group of enthusiasts loves details, figured I'd post up a few small changes I made over the winter hoping to pick up a tenth or two.

Car ran 11.89 @ 116.23 last year. 86 GT with 190 11R heads, SM2, 1-3/4 headers, reused cam (from an old build with Cobra intake/ AFR 165 heads); otherwise the car is full weight, back seat, A/C, your family friendly street car if you will.

Changes so far - finally hacked open my Systemax 2 to see the insides and do some porting. While I didn't get any pics of the porting work like a dunce, I'm fortunate enough to live within a stone's throw of EthylCat, who welded it back up for me very nicely. Thanks for the great work, Steve!



Alongside that, I put a dial indicator on my rocker studs to see if they really flex under spring pressure when valve is open. Sure enough, they do even though it's very slight - at 6400 rpm I know it's even worse. So next purchase - Jomar one piece stud girdle:



Lastly, had to use tall valve covers to clear the girdle, and it turned out to be sort of a blessing. When marking up the spacer to see the transition of the upper to the lower, I came across some areas where the two were not aligned perfectly, to say the least:




The way I did this is set the spacer on the lower, bolted it down as if it would be when running, then took a sharpie and marked all the places I could feel a "lip" between the lower runners and the spacer. I then removed the spacer and used a rotary tool to grind away and smooth the areas, then placed it back on the lower to check alignment again. Rinse repeat until the lower transition to the spacer was perfect.

THEN I bolted the spacer to the upper to see where it was off, and that's why in the 2 pics above, you see metal on the other side of the spacer. So I took to my sharpie and marked every place metal was showing, removed spacer, ported away, put spacer back to check, rinse repeat until the transition was smooth. Note that there were also places the spacer covered an area where air would flow if the spacer wasn't there, so the spacer was bigger than the upper runner in some places, and smaller (restrictive) in others, so I had to carefully grind the spacer at an angle for the areas where it was restrictive in order to preserve the integrity of the runner, aka I don't want to just hog out the spacer to the size of the upper runner for fear of creating turbulence when air comes in and smashes against the lower intake.

In the end, the spacer now creates a nice smooth transition between upper and lower versus the restriction and turbulence that had to exist before. This, alongside using a set of Ed Curtis's thick lower intake gaskets to help out my head port to lower port alignment get to where it should be, definitely won't hurt things.

I'm also removing my EGR spacer and bolting the throttle body straight to the intake, which I ported the inlet out to 80mm to match the TB. The only change I haven't gotten to is 3" X pipe and later - 3" tailpipes and exhaust. If I picked up 2-3 tenths and 1-2mph from those changes I'd be happy.

Here is a pic to whore my car out:




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[danco86]

Very nice
Those are pretty impressive numbers!

[rock4451]

Thanks danco! The warm weather can't get here fast enough.

[FoxFords&FFR's]

Thats a great MPH for that ET. What was your 60ft time? Can you describe what the intake looked like inside and what you did to make it flow better? Taking weight out is a no brainer for better ET's. A dedicated drag suspension will go a long way to help whittle down the ETs. Everything is a tradeoff though because your handling suffers on the street. If thats not a big concern you can run no front sway bar and drag springs and either coilovers or 90/10's or adjustable shocks and struts. Its all the little things that add up to lowering your ETs, thats the whole object of blueprinting. Good Luck and thanks for sharing.

Mike

[cb84capri]

It's all in the small details. Looking good so far. How much did you pick up swapping from the AFR 165s and Cobra intake to the 190 11r and Systemax? Have you noticed any mushrooming on the top of your valve stems in your 11r heads? I saw this video the other day which is why I ask:

https://www.youtube.com/watch?v=eQluE_gyTNY

Cale

[rock4451]

Thats a great MPH for that ET. What was your 60ft time? Can you describe what the intake looked like inside and what you did to make it flow better? Taking weight out is a no brainer for better ET's. A dedicated drag suspension will go a long way to help whittle down the ETs. Everything is a tradeoff though because your handling suffers on the street. If thats not a big concern you can run no front sway bar and drag springs and either coilovers or 90/10's or adjustable shocks and struts. Its all the little things that add up to lowering your ETs, thats the whole object of blueprinting. Good Luck and thanks for sharing.

Mike

Thanks, Mike. My 60ft was 1.69 on that run, my suspension is literally bone stock with the front swaybar removed. About the intake - you can sort of see in the picture I posted, that the #1 and #8 runners sort of have a little step down before them (in the pic you can see on the far left side, that step down to the runner from the top, also pic below with red circles), so I ground down on the side where it blocks the runner sort of, and I smoothed out the transition where air makes the 180 degree turn to go into the runners. The Systemax has a good design in that the transition is helped by use of the Coanda effect. Long story short, when the air is rushing in to the intake through the throttle body and into the upper, it likes a surface to grab on to when it makes the turn to the runners, the pic below shows what I mean - you can see the thick rounded "rod" for lack of a better word, in between the upper inlet and the runners. If you have a quick, short (not rounded) turn there, the air doesn't make it's way down to the runners as efficiently. I touched that up to make it as smooth as possible (slight casting flash along the entire length), and removed the bolt boss that is literally smack dab in the middle of the intake right after air enters the throttle body. Just a few minor changes, I thought about cutting open the top to shorten the runners altogether but opted not to.



The red circles show where I ground down to give the runners a better chance at getting more air, and the blue circle shows the "rod" I'm referring to. I also opened up my TB to a true 80mm, and won't be running an EGR spacer either.

It's all in the small details. Looking good so far. How much did you pick up swapping from the AFR 165s and Cobra intake to the 190 11r and Systemax? Have you noticed any mushrooming on the top of your valve stems in your 11r heads? I saw this video the other day which is why I ask:

https://www.youtube.com/watch?v=eQluE_gyTNY

Cale

Thanks, Cale. I never took it to the track with my Cobra/AFR setup unfortunately because I rolled that car and gutted it of the powertrain, and sold that to fund my upgrades for this one. On the dyno, the old setup made 319/321 but was out of breath at about 57-5800 where I shifted. It was also on a Dynapack which isn't a full roller dyno, it connects to the axle and measures there, which shows a slight advantage for numbers because you don't have the weight of the tire/wheel to spin as well. So I gained 31 horsepower/18 torque at the tires, which is roughly 38hp/23tq at the flywheel, plus this setup was tested on a DynoJet, so anyway, I say I gained around 40/25 at the engine.

I just had my rockers off when I had to install new polylocks for the girdle, and don't see anything out of the ordinary on the valve stem tips. Thanks for the heads up, though.

[rock4451]

Update. Had the 2.5" X pipe removed and a 3" installed. Noticeably quieter! Mufflers back is still 2.5" for now.


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