[Scarebird]

Thank you for the leeson on how these newer engines use blowers.

From those diagrams it is obvious a top draw intake is pretty much a no-go.

[Adecco]

Just what I am looking for under the hood of my 71

[RocktimusPryme]

That is awesome. I have been halfway considering a centrifugal unit on my firebird. This would for sure be an option as well. Im just concerned that if I added 150 HP I would be past the limits of the stock 400 block.

[darbikrash]

Originally Posted by RocktimusPryme

That is awesome. I have been halfway considering a centrifugal unit on my firebird. This would for sure be an option as well. Im just concerned that if I added 150 HP I would be past the limits of the stock 400 block.

Centrifugals are a good option as well. They do have very different boost characteristics as compared to twin screw blowers. Typically, centrifugals make their boost at a much higher RPM, with little boost down low where most street driving is done.

For a pure drag car, I think a centrifugal would be a better choice.

My goal with this project was to get a package that could be used on the street, fit under the hood, and make decent power even for a guy with unported cast iron smog heads and low compression. With this example, if you keep a sensible redline of 5500 RPM (or lower) you make all the power with cylinder pressure-not by revving it.

This is a lot easier on a stock block, and you can get respectable HP numbers and still get by with less than a full aftermarket block.

Not trying to say a forged bottom end and an aftermarket block aren’t an advantage- of course they are, but with modest boost, a sensible redline and the tight engine management that comes with sequential EFI, you can do a lot.

Here is a graph from Richard Holdner who probably dyno tests more blower motors than almost anybody, comparing boost curves from a twin screw (in this case a Kenne Bell) with a Vortec centrifugal.

Notice how flat the twin screw boost curve is across the range, and how little boost the centrifugal is making under 4000 RPM.

[imposter]

i want one

[Tom Vaught]

Very good post on the comparison of the two boosting units.

TV

[w72]

If this can work with a stock-looking shaker hood, it's a game changer for me.

[Chiefpmd]

Any chance you have the 3d scans of the engine alone to share?

[Fearne]

If there's an interest list being made, I know my dad and I would wanna be on it! He's got his '75 Grand Prix and I got my '68 Firebird.

[4zpeed]

Originally Posted by Fearne

If there's an interest list being made, I know my dad and I would wanna be on it! He's got his '75 Grand Prix and I got my '68 Firebird.

Welcome to the forum, you can click on "darbikrash's" name and use the private message option.

By the way everyone here loves pictures, feel free to start a thread and share some of your cars.



Frank

[darbikrash]

Originally Posted by Fearne

If there's an interest list being made, I know my dad and I would wanna be on it! He's got his '75 Grand Prix and I got my '68 Firebird.

I am creating an interest list, if anyone thinks they may want one, please send me a PM with your contact info and I will keep you posted on progress.

I am scheduled for two days of engine dyno testing at Westec sometime next month, so it will be interesting to see the HP numbers. I will be bringing several different pulley diameters, so we can see a good variety of boost numbers.

One other aspect of this particular system that I'll mention is the idle bypass feature. Below you can see a butterfly plate that is below the intercooler, this is used to bypass any boost made by the screws at idle, or at low idle conditions (such as highway cruising). Neither the screws nor the intercooler brick is shown in this view.



This bypass diverts all the boost at idle using the vacuum modulator you can see on the lower side of the blower. It is not electronic -it uses engine vacuum to actuate the butterfly and divert boost. I have this setup to start opening at ~8.5" of vacuum, and is fully open at 10" of vacuum. Any cam with more than 10" of vacuum at idle will work fine, which I think includes most "streetable" cams.

This is important because this system makes boost right away, from idle speed and upwards, with no lag and importantly- no blower surge. Also, these screws take up to 60 hp to turn at full boost, when you are at highway cruise conditions with high engine vacuum, all the boost is bypassed and it takes less than 1/2 hp to turn the screws.

I mounted the throttle body today, its a 102 mm.

[twov8sandat4]

This is awesome. With a Shaker scoop hat, this would be the dream setup for my 74 T/A.

[Jim Robertson]

Very interested in this setup. Looking forward to hearing the performance numbers. IMHO, This is a much needed piece.. Best of luck with the engine testing. .

[R 70 Judge]

Very cool! I’d definitely be interested. It’s hard to beat OEM reliability. If I could make a real 950rwhp and remain streetable I’d strongly consider this set up over going turbo.

Is there enough room to run -8 or -10 cooling lines from the rear of the block to the water manifold?

I assume PICO/EV6 style high impedance injectors fit no problem? I have Terminator X and don’t want to upgrade to HP or Dominator.

[R 70 Judge]

Is there room behind the tensioner assembly to retain my 12x crank trigger setup?

[darbikrash]

Originally Posted by R 70 Judge

Very cool! I’d definitely be interested. It’s hard to beat OEM reliability. If I could make a real 950rwhp and remain streetable I’d strongly consider this set up over going turbo.

Is there enough room to run -8 or -10 cooling lines from the rear of the block to the water manifold?

I assume PICO/EV6 style high impedance injectors fit no problem? I have Terminator X and don’t want to upgrade to HP or Dominator.

I've seen engine dyno pulls using the TVS 2650 that put out over 1000 crank HP using E85, one in particular was on a 366 CID SBF.

No problem on the high impedance injectors, the below the blower, in the valley setup that is pictured uses Holley 100 lb/hr flow balanced injectors with EV6 connectors, which are plug and play for the Terminator X. The Injector Dynamics 1050 also fits.

No sure what you mean about the cooling lines, the air/water intercooler mounted in the blower does not share engine coolant, it has its own circuit.

[darbikrash]

Originally Posted by R 70 Judge

Is there room behind the tensioner assembly to retain my 12x crank trigger setup?

Not sure. The 8 rib pulley stands off from the ATI balancer about 3/4", the space between balancer and the block might accomodate, hard to know without having the trigger wheel.

How are you getting the cam signal?

Sometimes a simpler approach is just to use the Holley dual sync distributor. This setup can also be configured for CNP/COP if you prefer individual coils.

[/url]

[R 70 Judge]

Originally Posted by darbikrash

I've seen engine dyno pulls using the TVS 2650 that put out over 1000 crank HP using E85, one in particular was on a 366 CID SBF.

No problem on the high impedance injectors, the below the blower, in the valley setup that is pictured uses Holley 100 lb/hr flow balanced injectors with EV6 connectors, which are plug and play for the Terminator X. The Injector Dynamics 1050 also fits.

No sure what you mean about the cooling lines, the air/water intercooler mounted in the blower does not share engine coolant, it has its own circuit.

I meant pulling water/coolant from the rear of the head to integrate into the cooling system. Looking at it again, I’m sure the extra lines can squeezed through to mate with the water crossover. It’s a cooling mod not related to the blower.

Cool. Those are the same injectors (holley 100lb flow matched) I’m currently using N/A on E85.

[R 70 Judge]

Originally Posted by darbikrash

Not sure. The 8 rib pulley stands off from the ATI balancer about 3/4", the space between balancer and the block might accomodate, hard to know without having the trigger wheel.

How are you getting the cam signal?

Sometimes a simpler approach is just to use the Holley dual sync distributor. This setup can also be configured for CNP/COP if you prefer individual coils.

[/url]

Thanks for the additional picture. It appears the pulley could be machined to squeeze in the crank trigger wheel between the balancer and pulley. ATI also makes a replacement shell with integrated magnets (can be configured for 12-1x) as an option. In the end it would not be a huge thing to figure it out.

I use a Holley dual-sync distributor for the cam signal. We initially got it running with only the dual-sync (cam and crank signals) but the timing was a bit finicky so we switched to the 12-1x with hall-effect sensor for more stability and resolution. I’m running Holley Smart Coils (CNP) with brackets to mount them on a Pontiac valve cover. If I wasn’t using smart coils, I’m confident the dual-sync would’ve worked just fine for all timing functions. The crank trigger is a Holley SBC 556-171 kit with a custom bracket to fit a Pontiac. On a side-note, I’m having some extra brackets made if anyone is interested in changing to a 12-1x setup. Just PM me directly so this thread isn’t muddied up.

Your LSA blower project is really cool! I look forward to more updates

[242177P]

Originally Posted by R 70 Judge

... extra lines ... water crossover ... cooling mod

That mod is deeply flawed. Coolant that has bypassed the cylinder heads results in lower temperature readings at the water crossover. Moving the sensor to the cylinder head would tell a different tale. HTH.