This is all in theory of course, because I'm not an engine builder. So let's dive into this:

Ever since I learned about Weiands mini blowers, ive liked the idea of one. Streetable, little wow factor when you pop the hood, and of course, more power. If I wanted to pull the l98 in my car, and add a mini blower, what else would you more experienced people add to the build?

Again, it's all hypothetical because I can't really justify the cost unless I had "I dont have to worry about a fancy steak dinner" money. Just curious about how one would build this engine.

 

The 142 or 177 blowers? They are cool. Could keep the L98 base motor, just freshen it up. Id do rods and pistons and run it on e85 for a bad *** setup

else pump gas and maybe a water/alky injection via plate on the blower for wot use.

id love to see efi on it but dont think they make port injector bases for those, so would have to be something like a Sniper type throttle body injection deal. Probably could work

 

Yeah, the 142 was specifically what i had in mind. First learned about em when kicking ideas around for an older carb'd truck. Might as well say I need things drawn out in crayon when it comes to internals, compression ratios, cams, heads etc.

I also probably should have searched the topic before asking....i didnt think itd be that popular of an option 😳

 

I ran a Weiand 177 at factory belt ratio on a bone stock 1-ton TBI 350 crate engine. The had 1.6 rollers rockers and headers. I had a 454 TBI on top of it. It was a 700r4 killer. It made ~425 tq at the wheels and 325 hp at the wheels at 10 psi. I prefer the 177 to the 142 and the Edelbrock E-Force is even better than the Weiands. The E-Force is a more efficient setup and has a bypass valve. Bypass valve saves fuel when cruising by allowing the blower to essentially idle along.

 

Are you looking fir a build recipe?
Do you want to build it on your current L98 350 or start with another engine as a base.

The 142/144 weiand blowers do sick things to a 305 cid sbc..
I like the 144 blower because it comes standard with the much better 10 rib pulley drive system.

The Weiand 177 makes more power on either a 305 or a 350 sbc..
The Blower Shop's 192 TBS billet blower is even better. A bit more money.. A lot more blower.

The Edelvrock /Eaton E-Force 122 HH lil blower is great on these sbc street blower engines.
You want a LOW engine compression ratio.
Alliws running agressive boost on pump gas (92++)
7.5 to 8.5:1 CR.
You want cylinder heads that flow more than stock
can be well ported stock or aftermarket.
A larger chamber head alliws for the lower CR.
A blower needs to eat. It wants a big carb. 750+++++ cfm or even 2 carbs. Bigger is better.
A blower motor needs a camshaft that moves air in and out of the engine to make power.
Most all of the popular 110 LSA catalog cams make very good street blower cams.
Blower engines like headers and bigger exhaust to move more air out.. (can be shorty type headers. + 2.50" dual exhaust. Or big 2.50" into 3.50" Y pipe exhaust on a Fbody..
The fuel system will need upgrade to pump more fuel capacity to feed more horsepower..

Start with what engine you want to begin with and your tarhget horsepower goals.
The 142/144 mini weiands are good for up to about 480 hp on pump gas.. The others are 500++ hp capable..
Is 480+/- hp enough or do you want a lot more HP?
Avoid choosing a blower that is just not capable of your HP output goal...

Again if 460-480 hp is goid the 144 gers it done well on a low cr modded 305 or 350 sbc.

On ALL these roots blower engines the air charge cooling effect and anti detonation effects of Water/Methanol Injection really allows you to crank up the blower drive ratio to make more power with more boost yet at lower charge temperature.

 

On a Fbody car you can plan on needing a 3" to 4.5" hood scoop or cowl induction hood to fit the air cleaner on the blower , depends on which specific blower you use. None fit under the stock hood.

While a 350 cid supercharged sbc ultimatly makes a bit more horsepower and torque. do not discount using a hopped up 305 cid sbc as a base.
Especially if you got one on hand.
As I said the 144 blower does sick things on a 305 on a strick budget. A low cr dish piston 8.4:1 cr LG4 305 is a good start point for this. It will need some mods and upgrades.

A low cr dish piston 350 is another good base to build on.

If you don't mind starting with the bigger taller weiand 177 blower you can make some serious power on either a 305 or a 350 engine.
It simply can pump more air.

 

Boost is not the end game.. Boost is not a measure of engine power and torque output.
A restrictive engine (small cam, small stock heads etc) will show a higher boost guage reading but not that much power output.
A more powerfull base engine make MORE supercharged power while using reasonable boost levels that are pump gas friendly.
A blower basicly just amplifies what the engine its bolted to is capable of.
More net engine air flow in and out equals more supercharged engine horsepower and torque output.

 

So..... question:. Does your current L98 350 engine have the oem # 083 cylinder heads?
And does it have the factory OEM pistons with the slight dish and 4 valve reliefs?

 

As far as I know, my current L98 is a stock engine. Beyond that, I don't know about the specifics. Is there an advantage to these parts in particular?

Im not looking for a wild amount of HP, so if this build ever happened, I'd be very ok with anything between 325 to 400. I know that's a big range but my goal would just really be a fun to drive, reliable cruiser that would give some smiles per gallon as opposed to a high HP car trying to keep up with boosted LS cars at the local 1/8 mile.

Idk that im looking for a recipe per say, like im not asking for a parts list, but just more of a general guidance to gain better understanding on how this build might go.

Knowing I would need that tall of a hood is kind of a turn off. Im not opposed to a small cowl, but anything in the 3 and 4 inch territory is alot.

I appreciate all the info!

 

400 hp is a cakewalk with a 144 blower on your L98 with home ported L98 heads (083 castings) and modest 6-7 psi boost. (Use 2 stacked .040" felpro head gaskets on this to lower the compression ratio) . You'd want a high perf hyd roller cam to let the air in and out.
. EG Melling 22280.. EG Elgin # E-1229-P. EG elgin #E-1135-P EG Elgin E-187IP

Be generous with the head porting. make 'em flow.

A HEI vacuum advance Diz (locked out mech advance is fine.. (set at 28 to 32 BTDC)
In this locjed out mode the HEI tends to self retard at high rpm so no need for boost retard at modest boost. and easy 28 to 32 Deg timing.
Retain the vacuum advance.. (goes to the intake manifold)...
These are the basics to low budget supercharge that 350 engine.
A bolt on BOSS 429 style Mustang hood scoop gets it done. (the biggy size version) 3.50"
You can paint it body colour to match the car or leave it black... The 144 blower is the better buy as it comes with the better 10 rib blower pulkey/belt system..
Blower pulley drive ratio select:
2.00:1. 2.10:1 2.15:1 2.28:1 dial in to suite the amount of power you want.

 

Stacked gaskets? I didn't know that was even a thing. Definitely learning some new things. I might need to source a second car for this idea. I don't know how I feel about hacking up a TPI car to go carb'd.

 

You don't need to hack it up..
You can park the whole TPI top end on the shelf and build on the L98 short block.
Or source another 305 or 350 engine to suoercharge. Park the complete TPI L98 engine on a engine stand and store it.
Doubleing up head gaskets is a low cost way to lower the engine compression ratio. on that L98 engine.
It works. 8:00 to 8.5:1 cr is a good zone to target fir this.
A 305 with these same mods is more than 400 hp capable also . Its the same prep job.
People give away good running 305's.
If its not a roller motor version use a hyd or solid lifter flat tappet cam.
EG: Comp XE 274H-10. eg: Lunati street solid cam #401A2Lun

 

Another method to lower the engine compression ratio on a 350 or a 305 is to swap the cylinder heads for the large chamber version sbc heads.
76 cc. EG. #441 , 920, 487,. 336. etc.. All need home porting also to increase aie flow.
Avoid the crappy 882 and 462624 castings.

But double head gaskets works fine for low moderate street supercharging to tame down the CR for 6-8 # boost on 92 pump gas with easy spark timing to let it live.

 

How do you get around the computer stuff when switching to carbs? Just leave stuff unplugged? I understand the ecm won't be controlling the air/fuel on the car anymore, but will that cause issues with other operations of the ecm?

 

You can leave it in the car. Ya unplug it.
On this carbed engine you don't use it.
you need to upgrade and mod the fuel system for the carb.
Use a 85 era old school GM HEI with vacuum advance diz. All the electronics for the TPI is not used.
You might leave the fuel pump and efi fuel line alone.
Add a new 3/8" fuel line with tank pickup tube and a Carter P4070 electric fuel pump for the carb.
It has the right pressure and flow volume for this carb.
This all allows you to revert back to the stock
TPI EFI at a later date.
You don't need to trash the car nor discard any of the OEM stuff.

 

I have a question/concern with stacking head gaskets.
Doing this will move the heads further apart from each other..... and the intake sides of the heads will spread apart quite a bit also.
How do address intake manifold port alignment and sealing? More stacked gaskets? Pushrod length (at the very least) is going to change.

 

If using the TH700r4 OD trans with this supercharged engine.. A few things.. Do not engage the lock up clutch in the tork converter if when @WOT.
Do not attempt to go WOT when in OD.
The trans OD gear and converter clutch are not intended to transmit WOT engine power.
These are both only intended for steady part throttle cruise driving.

When going WOT put the trans shifter in "D". VS "OD"

Getting the trans TV cable geometry on the carb correct is critical ir the th700 R4 trans will burn up.

 

Yes the combined change in net head gasket thickness to lower the CR will effectively make the pushrod length that much shorter.
You can check that and the effect on rocker geometry on install.
If the intake won't seal if using stacked head gaskers you can stack intake gaskets or use thicker ones as required. 1 or 2 intake re-torques msy be needed but do not over torque the bolts. It doesn't help.. But the re-torque will.

 

Hey! Sorry to jump in this thread with limited experience, but I'm wanting to put a 144 on after reading what you have said. I have a bone stock 1989 305 TBI. My question is would it be okay to slap on a 144 and a carb and call it done. Or would I need to make some mods to the heads and cam as I have seen from other threads. Or just do an LS swap lol, thanks!

 

If you're willing to spend the money on a blower, don't skimp and use the stock heads. A decent set of aftermarket heads can be bought for less than a grand. It'll be night and day difference.

 

The 144 blower on your 89 tbi 305 will work very well with a few changes.
Ditch the TBI swirl port cylinder heads.
Way too power restricted.
Any of the 64 cc to 76 cc (non TBI) heads from a 350 with 1.94" intake valves will work great on your lil blown 305. 2. benefits.
1. lower compression ratio.
2. bigger intake valve (1.94") and non swirl ramp port. More flow.
All the OEM 350 sbc heads need generous home porting as they all are relative liw flow in stock as cast form.
All respond to generous hand porting for more supercharged power.

You want to ditch the tiny OEM TBI engine camshaft.
Any cam with 218 to 230 .050" duration on 110-112 LSA is great with the 144 blower.
EG: Comp XE 274H10. Comp XR 282HR-10
Melling cam #22280 or say even a comp 280h-10 magnum cam.
On ALL the typical 110 LSA cams you can add to supercharged performance by advancing these cams a hair more . EG: 110 LSA 106/114 centers.
Move the cam for 104/116 centers (slightly more advanced.)
use suitable high perf valve springs.
You don't really need a "blower cam" for this.
Use a 750++ cfm carb

A 144 does sick things to a 305 with these blower friendly power enhancing prep upgrades.

The stock out of the box blower drive pulley ratio
(1.96:1) will get you started. easy moderate boost.
Lots more power and torque with more agressive blower pulleys (2.15:1, 2.28:1) drive ratios.
This is why you want the lower compression ratio a 350 sbc head swap (64cc to 76cc chamber volume) provides on your 305.

Your 750+ cfm carb may need minor rejetting
(richen up the secondary jetting a bit)
The car's fuel system must be able to flow enough fuel (VOLUME not pressure) to feed your much more powerful supercharged engine.
The fuel lines and fuel pump may need upgrading.
The oem EFI stuff will not work.
The stock TBI swirl port heads will be a big disapointment. It will run and drive but the power will be very restricted by the swirl vane in the intake port. A supercharged engine wants to breath deep to make power.
Avoid the worst of the worst of the 350 heads.
pass on any all #462624 and 882 heads.
crappy ex ports thin crack prone crap.

 

I'm currently porting and modding a set of the old
pre 1975 #920 350 76 cc heads for a supercharged 305.
Very simular to the #441 heads.
non restricted ports that get good with the porting.
heavier castings.
1.94/1.50 valves. 76cc chamber dives down the compression ratio for agressive powerfull boost on pump gas. (2.28:1 blower drive)
You can too.
Another great choice is any all of the old 327-350 camel back heads with 1.94" intake valves.
EG. 291,462,186,041 etc.
(the heads with the 2.02" intake valves will not work on a 305.
1.94" is plenty big.
a 350 L-31 Vortec head (062 or 906) is dynomite on a blown 305 with correct vortec pattern supercharger intake manifold.

Any time you use a 350 sbc cylinder head on a 305 USE a 350 head gasket. Not a 305 head gasket.

 

Just remember that any head with a 2.02" valve will not work on a 305. Stick to heads that have a 1.94" intake valve for a 305.
All these entry level aftermarket sbc heads are a great start point if when you finish the job by porting them to kick up flow.
EG Dart / World Product SR heads.
Get very good once ported.
EG any all of the aftermarket vortec style heads that have a 1.94" intake valve.
(use correct blower intake that has a vortec bolt pattern).

 

Yep, he said he's got an L98 but I guess that could change. I've had good luck with the Trick Flow 175's on 305 based engines but that was a long time ago when they weren't so expensive.

 

Wow, you are great! This is a lot to take in and plan for. Thank you!! I'm sure I'll need to ask more questions down the road.

 

Stock swirl ports made massive TQ and plenty of HP when I had them under a Weiand 177 even with the stock TBI cam and 1.6 roller rockers. It made a very flat power curve out to 6,000 rpm. What other stock head, stock cam TBI engine with TBI on it do you know making 400+ HP at the crank and a 700r4 shredding ~500 ft/lbs.

I had the factory TBI EFI. B&M had a TBI truck specific 144 too.

 

400 hp under a 650 hp capable Weiand 177 blower.
Thats a big cork. Its all relative but the TBI heads and cam create a brick wall to power. Even on a blown 305. The Weiand 177 blower does sick things to a 305.. 500++ street hp.
You want to let it eat. a bit... (Modded heads and cam) Lots of ways to skin a cat.

 

I would use the Edelbrock 122 kit. It's a couple hundred dollars more, but as of December 2022, it is in stock while the Weiand supercharger kit is not in stock. Also, the 122 utilizes a new rotor design, the M122, the same used in the 2008 Shelby GT500. At the same boost level, on the same engine, more power should be made due to the better efficiency.

 

Agree.. The Eddy/Eaton design E Force 122H blower is a beauti. There is a kit specific for Vortec cylinder heads. Yes a bit more powerfull than the 142/144 blowers as its a bit more efficient.
The vortec head specific kit is a few dollars less than the other for 55-86 sbc heads.
A few bucks more.. A more advanced more efficient supercharger design.