Alright, I believe we are on the downhill slope (maybe?)

All machining work on the block is done, I'm halfway through porting the head, and all that's left to order before we have a complete long block is stuff like bearings, gaskets, rings, etc.

BUT... I have come up with a whole new slew of questions now. I will organize them in groups:

INTAKE

I have several questions on the Aussie intakes, if you have any experience with these (or shoot, even Hpak experience would be appreciated) please, feel free to chime in!

I have the 2 barrel version of the aussiespeed hurricane, but I'm wanting to step up to the 4 barrel version so I can use a wider variety of carburetors. I'm wanting to run the carb in an east/west fashion, and the thought has crossed my mind of putting a divider (or even a partial divider) in the intake. Now, my questions are:

1. Does the hurricane 'ram tune' at any particular rpm? I've read it starts to fall off around 5500, where (in your opinion) does it start to come on? I know that motor I built with it started to pull hard around 2500, but it was assembled and tuned so poorly that I'm not even going to use that as a judge.

2. What limits the top end on the hurricane? Not enough plenum? To small of runners? Is it something that could be modified to extend the powerband? Does anyone run a spacer on theirs?

3. Has anyone ran both the long and short aussiespeed intakes. Did you find any noticeable difference in the way they performed?

4. Would it be worth it to buy a new intake? I'm looking at $600 for that option, not to mention the modifications. I do have some parts I could sell to re-coup the money, or would I just be better off to mill the top off of my 2 barrel intake and start from there?

HEAD

Alright all you head porting gurus, I'm working on a peanut head for a 'street/strip' build that will see a lot more street time than strip. I'm going to be using an OCG346 and 10:1ish SCR, and I'm shooting for as much torque and as wide as a powerband as possible, while still shooting for ~200hp@crank. I'm wanting velocity and as much low lift as I can to help achieve these goals. So far I have slimmed down the intake valve guides, slimmed/rounded the exhaust guides (little tighter there, not as easy as the intakes!) and opened up the bowls on the exhaust side some (had to to make room to work the guide) and done some work on the exhaust short turn.

My real question lies here:



How much should I open up the bowl on the intake? I thought I had seen a formula/rough estimation based on valve size and intended use, but I'm unsure of where I found it to study it again. These are the stock seats, I plan on running standard O/S valves. Does anyone have recommended diameters? Same goes for port size, but if all else fails I'll just open them to Fel-Pro size and call it a day.

Well, that's a decent start to some of my questions I'll add more as I think of them.

Oh, and if you'd be so kind as so quote the question or excerpt when answering/replying, it'd be greatly appreciated Does wonders to help me (and everyone else) follow along!

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1976 Dart Sport
Currently under revision

I would not bother with a divider. Maybe later after everything is tuned, but this will be a "last few % item" and the outcome will be hard to predict.
The 2bbl long runner I used was a monster down low, even with a big cam. Hard to respond w/o knowing your full motor buildup, but I can say that intake responded better than any I have ever tried (many).
Hard to say for sure, but I have measured runner areas and they are smaller than a Clifford and close to the same as stock. So, I would vote for runner area being the limiter, possibly followed by runner length being too long for high RPM. You will have to build a healthy engine to get it to pull hard past 5500 anyway.
I tried the short runner and that also was not super on the top end, so that leads me to think runner area is the limiter and not length.
I would seriously consider running a Holley 500 2bbl. You can make plenty of power with that on the Aus 2bbl long runner. Again you will need a fairly big cam and well ported head to pull hard past where the intake will limit you. 200 HP will be no problem with this intake and a Hly 500.

HEAD

The circle you drew looks pretty good. Buy the engnbldr 1.70/1.44 valves and get your machine shop to roughly cut the seats to fit those valves, then take it home and port it yourself (to your circle, w/new seats) and take back to the shop for final valve job. You do not need to enlarge the port openings much (maybe 1 mm all around). Most of the gain is where the valve seat transitions into the bowl. DO NOT try to smooth out the area between the INT and EXH valves in the ports, as there is a rectangular water jacket there and it is not hard to hit water.

Hope this helps,

Lou

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Home of Slant6-powered fun machines since 1988

may not be an option, there has been a set of 1.44 exhaust valves on E bay for a while, but no intakes. I tried contacting the seller,, engnbldr, have not received a response.

I talked to him 6 months ago. At that time he was sold out of intakes and did not plan on getting any more. My impression was that the exhausts will go the same way.

_________________
--> Check out my FI Turbo build <--
--> And the race truck build project <--
--> The Diesel Corvette <--

Chev intake 1.72 and exhaust 1.50 are readily available. They can be used with matching springs and retainers.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

'SI Valves' also carries 1.70 and 1.44 valves for the slant.
--> http://www.sivalves.com/

_________________
--> Check out my FI Turbo build <--
--> And the race truck build project <--
--> The Diesel Corvette <--

Thanks Lou,

Glad to hear its a monster down low, as that was a concern of mine. However, I'm not real eager to run a 500 Holley. I have a few reasons (although none of them may be legitimate )
I've heard they are hard to tune for the street
I'm afraid cruise mileage would be abysmal
It's big but at the same time it's small... Like, it's really large for a 2v but only flows ~350cfm on the 4v scale
I have both an AFB 500 and a Holley 450
Now, if I could find one of them progressive 2300 (2305?) in 500 cfm that'd be the cat's meow! I'm not even sure that was even made, not to mention the rarity if it were...
Then I must have bought one of the last few sets, as I purchased some roughly 6 months ago. I plan on using them, although the Chevy valves look to be a great option as well.

Which brings to mind another question:
Does everyone run a 45* seat angle? I'm thinking about running a 30* on the intake, for better low lift flow. Has anyone tried this?

Oh, and for full motor specs (as far as I have figured out anyways)
Late 70s cast motor, k1 rods, kb239 pistons, 3.445 bore
I think the pistons should reside .008 below deck, 3.5x.038 head gasket, and 58cc chamber.
OCG 346 ground on a 109lsa, hoping to set the intake centerline at 100 or 101
Should be 9.97 SCR, 8.11 DCR.
Ported peanut head, 1.7/1.44 valves, Aussiespeed intake, dual dutras with 2" true duals.
Thinking MSD for ignition, 904 trans with generic 2300-2500 stall (I'm just hoping it stalls 2k) currently 2.76 in a 7.25, 24" tires.

Also, if dusteridiot drops by, (or anyone else that like playing with DCR numbers) what numbers are associated with what grade of gas? I plan on tuning and possibly running 89/91 all the time, but if one were to build a 91/93 only motor, what DCR numbers would that be? 8.3? 8.5?

Thanks all!

_________________
1976 Dart Sport
Currently under revision

Grade of gas ........

The DCR is part of it . Gears , Trans type, usage, climate ....all play a part.

The other thing is fuel blend . Iowa corn gas 87 is nothing like Saskatchwan no ethanol 87.
Here Chevron 94 was tested and turned out to be 91.....not fun if your mill is built for 93.

I was able to run 87 (mostly ) with a DCR of just under 8,,,,,with a light car , rural or highway driving , temperate climate , 5 speed , 3.23 gears , and 26" tall tires. Thats the combo thsat worked for me....where I drive....the way I drive. Your experience will absolutely be different.

I now build everything for 87.....so I can travel without travail. How available is good 91 where you drive? 93?

All the calcs I used allowed you to chose a fuel....I stray toward the conservative side.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

91 is getting to be more available, corn and no corn varieties. The quality of the fuel is beyond me though.

And to be honest, I have absolutely no clue what this car weighs... I'd guess 3500 if I had to. Mostly stock, but it came with those half-ton bumpers...

And, I'm unsure what you mean by climate? This is lake area, fairly humid, at roughly 1000ft above sea level.

I wasn't sure if certain characteristics of the slant made it different than anything else when it came to a subject like this or not.

Thanks Sandy!

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1976 Dart Sport
Currently under revision

A heavier car with higher gears and a low stall auto in a hot hilly climate is going to require more detonation control than a light standard trans car with low gears in a cool flatland .



The trick is to try the calculators and play with the numbers.

Cam , compression , convertor and gears is the short form.

Figure the rpm you want at a target speed.....for max torque
Say 3000 rpm in OD at 100mph. Maximise torque via cam and ignition timing for 3000 rpm. Target cylinder pressures at 3000rpm to desired fuel via DCR. ( this is how my current car is setup)

Its a lot of headwork....but gives excellent results for little money
It takes hours and several calculators .

My toughest one was 2200 lb car 10.5:1cr 4500 stall, 10.5:1 final drive, 35" tires, 5800rpm, 94 octane fuel. It took a while but I found a very good cam used in an oval track application.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

I may be in Ava MO in March.....

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Can be run on 87 regular, depending on your distributor recurve and as Sandy said setting up your gear ratios and tranny properly....

89 would be plenty safe, 91-92 would be a waste.

9:1 DCR would be mandatory 92+ octane.