FrontEngineDragsters.Org Forum

Drag Racing Discussions => Drag Racing => Topic started by: jaded13640 on August 01, 2019, 08:06:00 PM

Title: New to supercharging, need some pointers
Post by: jaded13640 on August 01, 2019, 08:06:00 PM
Hi, I've been using fuel injection (Enderle Bird) and methanol for many years but I've never had the opportunity to do a supercharged application until now. We've got Duster bodied tube chassis car that weighs right around 2600 pounds. Loose converter, hopefully it's appropriate for the situation, and we picked up a stripped 671 and an additional Bird with the "K" series barrel valve. It's been suggested that it'll need to at least be respooled or just use the cube. We use iron 440 Block, bored and stroked to 500" and Stage V Hemi conversion heads. We'd like to see some low 8s and maybe an accidental 7 would really make my life complete.

I understand that a good blower cam, like a good nitrous oxide cam, is rather specific to supercharging. We have a very aggressive solid roller that I need to see what the specs are...maybe it'll get us by.

My first question to the blower guy was "what compression ratio should we use?" He said that with methanol you can go all the way up to 18:1 but he suggested we'd maybe want to stick around 12:1 and start by spinning the blower 25% overdrive. Fine with me if that's correct.

So those are the question I need to start with, you guys may need more info but I need to start by know what compression ratio will be the most friendly so I can get pistons and rods ordered. We're going to need lots of parts and we also don't yet have a blower intake. So if anyone has some good used stuff we can use, let me know.

Thank in advance,

Wayne
Title: Re: New to supercharging, need some pointers
Post by: GlennLever on August 02, 2019, 04:57:46 AM
Compression wants to be high. the way you get there is an argument. I like running static pressure low and let the blower do the work to increase you compression. finial compression of 18:1 might be a little low.

cam is important, however if there is not a bunch of over lap between intake and exhaust, you can try it out. You will want to change the cam at some point.
Title: Re: New to supercharging, need some pointers
Post by: jaded13640 on August 02, 2019, 09:38:45 AM
Excellent, thanks for the response. So you think with a stripped 671 and 12:1 would be a little low? If so how much? Your personal opinion on it is fine. Thanks for the cam info too.

Wayne
Title: Re: New to supercharging, need some pointers
Post by: Paul New on August 02, 2019, 03:57:17 PM
Im not a Hemi guy but, what I say is 12-1 is too high if your just starting out high static compression does not give you much of a tuning window and you will need it!
Title: Re: New to supercharging, need some pointers
Post by: jeff/21 on August 02, 2019, 04:16:39 PM
we ran 9.2-1 20% over littlefield 8-71 496 BBC on alky 1500 hp on dyno 9000 rpm on the straights using chart gave use 22-1 with the boost.
so 12 -1 seems a high but ran 13-1  6-71 30% over on a drag race 406 small block never dynoed
Title: Re: New to supercharging, need some pointers
Post by: dreracecar on August 02, 2019, 04:58:14 PM
10.2 to 10.5 is a good starting point for compression for alc, and fairly easy on the starter.  People will tell you that cam selection is a "Black art", it really isn't, Too hot or wild of a cam will eat up the valve train, save that for those that can afford it or is running a class that demands it. Let the blower and magneto do the work
Title: Re: New to supercharging, need some pointers
Post by: jaded13640 on August 02, 2019, 05:30:17 PM
excellent info! I'm cool with lower compression if that's the ticket.

I forgot to mention before, we need a hemi pattern blower manifold....I'm having a hard time understand why of all combinations THEY would be scarce but I'm not seeing any yet. Ideally used so save some money.

Wayne
Title: Re: New to supercharging, need some pointers
Post by: GlennLever on August 02, 2019, 06:27:29 PM
What is really important is the finial compression ratio. If you start with a higher static pressure you ask the motor to do more work, and the blower, does not work as hard.

If you start with a low static pressure you are asking more of the blower. Not a problem just a different way to look at it.

671 is a smallish blower which might need some help ......
Title: Re: New to supercharging, need some pointers
Post by: Supercat on August 02, 2019, 08:08:27 PM
We are running a 477 Buick blown alky. 671 to start and get the bugs out then we have the 871 when we are ready for it.
We are at 11.25 to 1 with a .070 head gasket.
Like many have said let the blower do its job add in fuel and good spark an have some fun.
Title: Re: New to supercharging, need some pointers
Post by: jaded13640 on August 03, 2019, 02:51:58 AM
And that reminds me of the other question I forgot to ask. I've always used the good Felpro gasket for NA, what do you guys that run blowers use for head gaskets?

Wayne
Title: Re: New to supercharging, need some pointers
Post by: Supercat on August 03, 2019, 04:07:43 AM
Copper head gaskets.
Title: Re: New to supercharging, need some pointers
Post by: Draw 3D on August 03, 2019, 07:52:37 AM
My little SBC has 11.5:1 compression ratio and in my opinion, if you start with low compression, you're going to have to spin the blower much faster and at a certain point, it will become the less efficient, and, the intake air will get heated more and that's not what you want to do.
Title: Re: New to supercharging, need some pointers
Post by: dreracecar on August 03, 2019, 08:57:32 AM
My little SBC has 11.5:1 compression ratio and in my opinion, if you start with low compression, you're going to have to spin the blower much faster and at a certain point, it will become the less efficient, and, the intake air will get heated more and that's not what you want to do.


   All blowers have a maximum boost they obtain till they start to cavitate, they are not linear and boost does not increase the more OD/rpms you give it.  Blower OD is to regulate when full boost is achived  say 5 over comes in at 60' while 25 over- 10' but on both runs saw a max boost of 22#

  Lower static lets the motor work easier from the start and then power on once the car gets rolling and has the rpm to handle the increased load the blower provides. Higher static puts more load on the drivetrain at the hit.
  But as Glenn mentioned-- find out which way works for you, I run what works for me and haven't change the basic combo in 24 years

  Alc maintains a 64* cooling charge into the intake port, If you are running gas then the intake charge must be cooled
Title: Re: New to supercharging, need some pointers
Post by: Draw 3D on August 03, 2019, 09:39:43 AM
Alc maintains a 64* cooling charge into the intake port
Don't think that is correct, temp at the intake port would be determined by amount of pressure and amount of air compressed mixed with the alcohol.
Title: Re: New to supercharging, need some pointers
Post by: dreracecar on August 03, 2019, 11:09:15 AM
Then why is it the my Intake manifold is cold after a run???
Title: Re: New to supercharging, need some pointers
Post by: Draw 3D on August 03, 2019, 12:56:41 PM
Feeling cold is not proof of maintaining a 64 cooling charge as you stated.
Title: Re: New to supercharging, need some pointers
Post by: dreracecar on August 03, 2019, 02:44:07 PM
Manifold temp probe says it does
Title: Re: New to supercharging, need some pointers
Post by: jeff/21 on August 04, 2019, 06:29:22 AM
on the BBC tried various types but ended up with copper and o-rings
Title: Re: New to supercharging, need some pointers
Post by: jaded13640 on August 04, 2019, 08:01:57 AM
Jeff, CRAP, I'm not o-ringing this block. Not now at least. You can buy those copper head gaskets that have something more to them than just a sheet of copper. Maybe others have had success with that?

dreracecar. For sure methanol runs cooler but I suspect the probe is reading condensation. The condensation would be able to happen if the fuel wasn't running cooler but I have a feeling were' talking about two different things. Since I figured how how to go fast NA, I've always used methanol and will never use gas again if I have a say in it.

I'm feeling like we'd better run 12:1 or just shy. I've always been a high compression believer but I respect the opinions I've heard here and I think 12:1 or even 11:1 would be a good  compromise. Like one member said, a 671 has it's limitation.

How about a hemi blower intake? That's the one thing we're struggling to find used. Any tips would be awesome.

Wayne
Title: Re: New to supercharging, need some pointers
Post by: jaded13640 on August 04, 2019, 03:14:43 PM
Typo, the condensation WOULDN'T be able to happen if the fuel wasn't running cooler.
Title: Re: New to supercharging, need some pointers
Post by: jeff/21 on August 04, 2019, 05:24:21 PM
 Cometic  MLS worked with the motors we built we had smooth block and heads but wouldn't work on a motor we bought that had a rougher surface didn't realize the problem until after o-ringing   cometic  has or will make any bore size or thickness had some strange stuff made.
Title: Re: New to supercharging, need some pointers
Post by: jaded13640 on August 04, 2019, 06:13:47 PM
excellent, thanks Jeff. Maybe I am going to be o-ringing this pain in my butt.

Wayne
Title: Re: New to supercharging, need some pointers
Post by: dreracecar on August 05, 2019, 09:30:45 AM
Too many issues had with the Cometic and SBC (surfaces prepped as needed) went back to copper and an o-ring- problems solved
Title: Re: New to supercharging, need some pointers
Post by: jaded13640 on August 05, 2019, 01:39:03 PM
Yea....son of a bird dawg... This is prove more complicated than parts selection. That's all building 500 strokers was about, and lost of clearancing for aluminum rods. I guess I'll be talking to the machinist that's going to bore it for us to cut the grooves in the deck. Dang it! LOL

Again, ANYONE knowing about a used hemi blower intake, please let me know.

Thanks for everything so far,

Wayne
Title: Re: New to supercharging, need some pointers
Post by: jeff/21 on August 05, 2019, 02:27:40 PM
I get my copper gaskets form Cometic
Title: Re: New to supercharging, need some pointers
Post by: uwizoquixyuso on February 21, 2024, 03:42:10 PM
Boost your health with our comprehensive solution; pharmacy for sale (https://fontanellabenevento.com/pill/pharmacy/)  today and embark on a journey towards optimal well-being.
 
Looking to purchase Aripiprazole? Find it effortlessly with just a click at <a href="https://johncavaletto.org/drug/priligy/">priligy 60 mg</a> , your preferred choice for pharmaceuticals on the web.
 
Your well-being is our priority; order https://johncavaletto.org/drug/priligy/ on the web and begin your journey to better health today.
Title: займ без отказа на карту
Post by: MicrozaiNot on February 22, 2024, 03:15:19 PM
Привет всем! Если вам нужны деньги «прямо сейчас», рекомендую воспользоваться услугой займ на карту без отказа (https://mikro-zaim-online.ru/zaim-bez-otkaza-na-kartu/). Это отличный способ быстро получить необходимую сумму без сложностей и долгого ожидания. Просто заполните заявку онлайн, и деньги будут у вас на карте. Удачи вам и легких финансовых решений!
Title: Reversible feeding, broadening tips, aneurysms; thrill.
Post by: ugabifunejp on February 26, 2024, 06:40:12 AM
Unlock your pathway to better health with our reliable solution. Order your vardenafil to buy (https://myhealthincheck.com/vardenafil/)  easily and begin your journey towards improved wellbeing.
 
Looking for a safe way to acquire your medication? With our platform, you can easily <a href="https://karachigo.com/pharmacy/">canadian pharmacy</a>  and maintain your health effectively.
 
You can obtain https://drgranelli.com/item/tadalafil/ for digestive well-being through our website.