Did some productive tunign with the 55 Bel Air today

[Aaron]

Pics tomorrow...

Today my friend and I got bored, so we went down to the garage to tune the lil bitch. She was already running GREAT, with decent A:Fs and ignition timing, but not perfect.

So we got a timing light, got a MSD distributor advance kit, got a $50 Autometer tach, and got a boost/vacuum gauge.

Our box has a boost retard feature, which pulls timing from 0-3* for each pound of boost. With the ignition where it was at, we ran it up with no detonation at 0* boost retard. That means it isn't advanced enough.

So we go back to the shop, and end up turning it to about 36.5, which is a lot. We go out, and it will start to ping slightly at higher RPM with 0, but at .5-1* retard, no pinging. This is good, for now...

Observations:
: Boost climbs pretty well, although I wish it had a excess valve so we could hit max boost at low rpm. It does not, but it builds boost after 1.5k. It builds pretty linearly, getting 8psi at 5000. But at 5500-6000, it jumps to 10 and climbs fast, up to 14 at 6000!!! So linear up to about 5000, then it climbs abnormally fast. But despite this boost, it drops power HARD. We think this is because of the restrictive exhaust. 1.5" equal full/mid length headers, true dual 2 or 2.25 crush bent exhaust. Tomorrow I am going to order 1.75"x32" Hooker Super Comps ($350), equal length, 3" collectors, and order piping for a true dual 3" and X-pipe ($500 with some Borla straight throughs).

: Power is strong until about 5000-5500, where it drops hard and fast, despite boost rising quickly (From 8 to 14 in 1000rpm...). Again I think a lot of this has to do with the exhaust not being able to escape fast enough with the increased boost. Keep in mind it has a real timid cam and close to stock iron heads with 202 valves.

: I am also going to order a smaller pulley. Despite the high compression and undersized blower, we are not getting much detonation at all for some reason. I think this is larglely do to the wet blower/charge, low RPM, and full MSD. I'd like to see a linear increase up to 10-12psi at 5000rpm. I'd REALLY like to incorporate an overboost relief valve, but the blower isn't made for that, so I better not...Maybe in the future.

: Needs new gaskets/seals throughout the carb, blower, and intake manifold.

fyi, motor is a stout rebuilt 406cu in small block with very mildly P&P heads with 2.02" valves, around 9-10:1 compression (Not totally sure...), a Might Demon 750 carb, Weiand 142 draw through supercharger (Need a 177, or better yet, 8-71), decent headers, crappy exhaust, full MSD6 boost ignition, and a mild cam.

[The Dark Side of Will]

: Power is strong until about 5000-5500, where it drops hard and fast, despite boost rising quickly (From 8 to 14 in 1000rpm...). Again I think a lot of this has to do with the exhaust not being able to escape fast enough with the increased boost. Keep in mind it has a real timid cam and close to stock iron heads with 202 valves.

Boost rises because VE is falling. Boost != power.

[Aaron]

: Power is strong until about 5000-5500, where it drops hard and fast, despite boost rising quickly (From 8 to 14 in 1000rpm...). Again I think a lot of this has to do with the exhaust not being able to escape fast enough with the increased boost. Keep in mind it has a real timid cam and close to stock iron heads with 202 valves.

Boost rises because VE is falling. Boost != power.

Ok, but why is VE falling at 5000rpm? Although it isn't built up, it should hold VE to 6000rpm.

What do you mean by Boost != power? Like boost doesn't equal power? That I agree with, CFM equals power. And I realize we are losing CFM, we must be, but the question is why?

[Indy]

Got the cam specs?

[The Dark Side of Will]

And I realize we are losing CFM, we must be, but the question is why?

1.5" equal full/mid length headers, true dual 2 or 2.25 crush bent exhaust.

Keep in mind it has a real timid cam and close to stock iron heads with 202 valves.

very mildly P&P heads with 2.02" valves...
...and a mild cam.

Not a mystery...

and order piping for a true dual 3" and X-pipe ($500 with some Borla straight throughs).

X-pipes freakin' rock.

Despite the high compression and undersized blower, we are not getting much detonation at all for some reason.

Not getting any detonation becuase you're not getting any air into the engine. AFR 195's and something with 0.5xx lift at the valve will give you some detonation.

[Aaron]

I would think that we'd be getting enough in though with the mildly P&P 2.02 heads and decent cam. I guess I'd think we'd get enough in at 8 manifold psi at 5000rpm that 0* of knock retard at 36.5* total advance would detonate. Maybe I am wrong though.

Were you being truthful about X-pipes? I generally feel they are a cirtical element in a dual exhaust, but a lot of the old schoolers believe true dual is the way to go, never having a balance or X pipe.

I talked to my dad about the motor's future, and mentioned a good cam, some better roller rockers, and AFR heads. But with this we'd need a bigger blower, and although the 177 is an upgrade, it still is too small IMO. I will be keeping an eye out though. We will be getting the headers and exhaust hopefully over Christmas time though.

[The Dark Side of Will]

Got dyno numbers for it?
A decently hot 406 should make over 500 ftlbs all motor.

If it's less than 650 at 8 psi non-intercooled, then I'd say you have some VE issues. I assume this engine has 6" rods? Running zero deck pistons? D-cups?

Detonation is all about having too much energy in the cylinders before combustion. If you're not having detonation issues, then you have low VE, low intake temps, OR lots of detonation resistance (how's the quench volume set up?) Aren't you also at pretty high altitude? That's going to reduce the mass of air in the cylinders and make the engine more detonation resistant. That's why 85 octane works in CO.


X-pipes are definitely outstanding additions to dual exhausts; especially with a square crank V8 because it has odd-fire banks. Each pulse (especially the two adjacent pulses from each bank) see half the back pressure downstream of the X-pipe. I read a magazine article in which an X-pipe with full exhaust made within a couple of HP of open headers on a pretty hot Olds (don't remember if it was a 455, but it wasn't anything to sneeze at).

[Aaron]

Got dyno numbers for it?
A decently hot 406 should make over 500 ftlbs all motor.

If it's less than 650 at 8 psi non-intercooled, then I'd say you have some VE issues. I assume this engine has 6" rods? Running zero deck pistons? D-cups?

Detonation is all about having too much energy in the cylinders before combustion. If you're not having detonation issues, then you have low VE, low intake temps, OR lots of detonation resistance (how's the quench volume set up?) Aren't you also at pretty high altitude? That's going to reduce the mass of air in the cylinders and make the engine more detonation resistant. That's why 85 octane works in CO.


X-pipes are definitely outstanding additions to dual exhausts; especially with a square crank V8 because it has odd-fire banks. Each pulse (especially the two adjacent pulses from each bank) see half the back pressure downstream of the X-pipe. I read a magazine article in which an X-pipe with full exhaust made within a couple of HP of open headers on a pretty hot Olds (don't remember if it was a 455, but it wasn't anything to sneeze at).

*drunk post*

I AGREEM TGHOU OUR 406 ISNT QUITE DECENTLY HOT, IT IS pretty stockisn.

it is definetely less than 650. best guess is around 400. i don thave any internal specs tho.

i do have loe ve, and cool intak e charge (wet blower, no hood, etc. we are at 6000 feet of hight and are running permiumum 91.

i will be using a xpiepe 2.

ill be sobar tomorrow, sorry will, thc so far for th ehelp.

[Series8217]

fnny how au coauld spel "*drunk post*" proapaerly youo undearagea dork ghwo proabably caanot get alcoohooll soo yuo juusstt acaet liek ur drunk!

[stimpy]

Hey, you don't have to be 21 to buy Listerine and aftershave...

[Series8217]

Hey, you don't have to be 21 to buy Listerine and aftershave...

ROR!

[Aaron]

shuit up you fucking lair!

[stimpy]

:la: aarons an al-co-hol-ic! :la:

[Aaron]

Update: 200ft burnout.

Did this yesterday afternoon with my friend in the car. I basically let the clutch out, went full throttle, and then slightly modulated the braked pedal. Holy shit was it rolling some smoke held at 4500-5000rpm. Then towards the end it got really fishy, and in a 50s suspension car, that isn't fun. So I had to stop it.




But later on that night, right before we started drinking, I ran it down the main boulavard here for 5min or so. Met up with a 1995 Trans Am 6-speed. I beat his ass smoking them into 3rd. We went from off the line, I annialated the tires through first, through second, and into 3rd. I had to let off around 4000 in 3rd becuase the car getsa REALLY unstable and scary, but I was about 2 car lengths ahead and still leaving black marks. The timing really woke this car up, and it loves the cold weather. I can't wait for the 177, headers, exhaust, and maybe after all of this new heads and a cam.

[Aaron]

Update:

The new headers will be going on over X-mas break. Unfortunately I need a new welder before I can do the full exhaust, so I'll run em open for now.

The plan so far is to get these, get a 177 blower and a smaller pulley, and then take the motor out. At this point I'll replace all the gaskets, and clean/paint every part. Then the powertrain will get covered as my dad gets to work with the body/paint.

I'm trying to convinve him that AFR heads and a Comp Cam are good, but he would rather play with the body for now. So maybe in the future I can do a head/cam swap, but for now I'll have to stick with what I got.

[Formula69]

Update: 200ft burnout.

Did this yesterday afternoon with my friend in the car. I basically let the clutch out, went full throttle, and then slightly modulated the braked pedal.

Using the brakes, I could do a 200ft burnout in just about anything. I used that method to burn at least 200ft of rubber in my old Firebird, with a stock 250HP 350-2V and Turbine 200 transmission.

If you want to impress someone, do it all motor - no brake tricks.

[Aaron]

If you want to impress someone, do it all motor - no brake tricks.

That's what usually happens when I try to race someone though.

The tires don't roll much smoke when its doing it just WOT, I mean they smoke a little, and leave clear blakc marks, and make a lot of noise, but the smoke is nothing like when I braked. I got to my friend's house 2 blocks away and smoke was still in the cab (No windows).

That car reeked for the next week, it was sweeeet.

I need a video camera. Oh, and I can't wait to get the new parts, which leads me to my next point.

The blower adds a significant amout of height to the motor. With a smaller air cleaner, 2" or so, it will clear the hood. However, I want to upgrade the blower. A 6-71 is too much, and would need 2 carbs. This is more than we want, and guaranteed to poke out the hood, which we don't want. The 177cu in unit sits on a different manifold, and does look to be higher than the 142 we have. I think it will still clear the hood, but I am not sure, and I don't want to drop 2 grand on a blower I won't want to use. Furthermore, a 177 still isn't enough. They make a 250 and 256ci/rev unit, however it is rare (Gets overshadowed by the 6-71), and I can't find pics of it for the life of me. But it is almost surely taller than the 177 and much too tall.

I wish Summit would post specs, from the lifter galley cross to the carb plate...

[Aaron]

Google Image search wins again.

The 250-256 series are dual carb blowers. This isn't totally out of the question, so long as it stays under the hood.

Looking closely, the blower looks to gain its displacement in length, not height...Looking as closely as I can, the 250-6 looks actually lower than the 177, and maybe even equal to the 142...

Ignore the gay scoop...


177cu in/rev

[The Dark Side of Will]

Whipple 3300, foole.

[Aaron]

Whipple 3300, foole.

I was wondering when someone was going to call me a hypocrtie bastard for all the shit I pile on roots blowers.

First, they aren't cheap.
Second, I'd have to build my own lower intake manifold.
Third, the belt drive would be a PITA to build.
Lastly, I don't want much more power, I'd say I'd be 100% content with another 100. And this won't be hard with headers, better blower, tuning, and maybe cam/heads.

These are all valid reasons, but just because it is a SBC. If this was for a N*, you'd have to do this for any blower, so you may as well go Whipple. But for a SBC, if you need more power, it can be found ANYWHERE. I mean I can buy a 6-71. If I need more, I can buy a 8-71. If I need more, I can buy an intercooler. If I need more, I can buy decent heads, cam, get more cubic inches, etc.

The roots SBC kits are easy and cheap. You buy them, buy gaskets, and bolt them on. Quite literally, the 142 was no more harder to install than a typical intake manifold install.