quote:

Originally posted by Alaskaracer:

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Originally posted by wideopen231:
My question is. Why so much compression? Asking because you have more than one time told not that much extra power with compression and really very littl gain after 14.5 or so.

Had to ask after previous replys on my compression questions. i all hinesty I agree with not much gain after 14.5, especailly with waht it takes to get much more.

As for gas or alky. I have never seen why either would not work equally or slight edge to alky. If womething with heads and easily correct so could run both why would you not do it? Can see where coment on cam makes lot of since on working better with one than other.Fuel volue and burn rate being my thinking.

I don't recall myself ever mentioning there is little power to be gained with compression ratios above 14.5:1, but I do know it's been said. However, I will disagree with that to a point. When I built my last combo, my head guy and engine guy both wanted my compression ratio high. It helps to offset the loss of air pressure at altitude since I was in Denver, Co. My last deal was set at 16.5:1. When I switched to alky, it responded very well and clearly made more power as the et's dropped and mph increased substantially. My new combo was supposed to be the same compression ratio, but somehow we ended up a bit high...that's ok. What's happening now, is that my engine is making more power from less fuel than it did before. Yes, I have a larger pump and nozzle jets now. But I'm bypassing a lot more than I did with a similar tune on the old combo at sea level. The engine is wanting a leaner mixture which tells me it's way more efficient than my last build. Yes, the heads, intake, and cam are a major player in that, but so is the compression. I'm still at almost the same timing and the engine is telling me it wants more....I'll take more power on less fuel any day of the week.

Not aimed at you. Curly has told me this and just wanted to ask why he now sees it as need. Agree if in lousy altitude it is benifit.

I have both side of it. High compression woke engine up and where it did nothing much. Combo as always. That is why ordered new piston for 15.5 and had extra left in pockets. IK can swap gasket for 15 to 12:1. May need spacer for intake but that it.

agian was aimed to op.

I typically do not go for this high of compression but on this one I am taking the advice of a few who are familiar with this type combination. Generally I like to be around 14 to 1. With this SB2 and the small chambers I could get as much as I wanted.

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I am with Steve on this one, I realize the benefits of EFI. It will start up nice and clean like a carb, you can have all kinds of safeties built in, You can set it to warm up quicker and use a lot less fuel.

But I really do not know much about tuning them and need to get a set up that is competitive from the start. I do not have the time or the money to spend 2 years learning and tuning the thing.

A competitive set-up can be achieved on a chassis dyno or even a T+T at the track in EFI. If an engine dyno is preferred and can accommodate the EFI controls then this way.

The learning curve is as tough as you want to make it. Some prior reading, video learning instructions and laptop practice is all that’s needed. Laptop practice of just loading the program, understanding where to look for what you want is key. Once that is somewhat mastered, much falls in place as to how you program the system and continue on.

Data acquisition from EFI is excellent and some use an interaction of the DA to the program….ie an rpm position you view in the DA shows a cursor position of what you have programmed and where. I like and find this feature helpful.

You wrote in prior replies that you only use O2 readings, and one for each cylinder to tune with. Then somehow you mechanically try to achieve what you think is the correct/ best for each individual cylinder by changing a pill/ jet/ pressure/ relief to get what you want.

In EFI, one would use the table below. The programming manipulation of what you want is far superior to anything mechanical imho.



As I wrote in a prior reply……. Install the ECU with what you have now, continue to use MFI as always, collect all the run data in ECU and learn how to use the system without tuning. Use the ECU as your new DA. Then when comfortable (a yr from now, whenever, never), switch to EFI intake manifold, plug in the injectors and go.

Tuning with EFI using the Learn mode is easy. You program the AFR@rpm you want and ECU adjusts to achieve this setting and creates a learn table that you can use to correct the fuel map to run in open loop and tighter closed loop adjustments.

btw… I’m also writing this for the possible benefit of others that might be interested, read, but never write.

Markemark, You sure make it sound easy.

Part of my decision will be after Dyno. In the 4.60 outlaw class any electronics is legal. If I continue to run NE2 then very little electronics is allowed. If I make enough power to run the Outlaw class then I will be ripping all wiring out of car and starting from scratch. Plus new fuel cell and radiator to move weight around.

For O2 sensors I use a RPM data logger and tune to best performance we got on Dyno. Pretty easy.

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Originally posted by Curly1:
To answer a few questions, I am going to need all the power I can get because I want to step up to 4.60 class.

Bruce, I know you are a Small Block guy, but is the idea of eventually going to a Big Block completely out of the question?
All of these dilemmas would be easily solved with cubic inches and big heads, and you could still run your fuel of choice (Alky)...

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Originally posted by FootbrakeJim:

quote:

Originally posted by Curly1:
To answer a few questions, I am going to need all the power I can get because I want to step up to 4.60 class.

Bruce, I know you are a Small Block guy, but is the idea of eventually going to a Big Block completely out of the question?
All of these dilemmas would be easily solved with cubic inches and big heads, and you could still run your fuel of choice (Alky)...

Actually I have a brand new 565 BBC with new 871 Littlefield stripped blower, Dart heads, new Crower shaft rockers I could run. I have not assembled it yet but will probably set it up as my back up motor. My thinking when I was buying parts and all for it was that I would not have to step on motor hard to run number. Change pulleys to compensate for air density to run number. Still in the end a blower is maybe 30% harder on crank, rods and pistons than NA motor and a blower motor is almost like on or off.
With NA and a carb I could use a restrictor plate if I made enough power to run number.

Big part of this is on my old combination I spent a lot of time, work and money testing and getting car to run number in all weather. I had it working then I could concentrate on my driving. I think going NA if I can would be quickest, easiest way to get back car running number and start getting good weather data. Last two years driving several cars different combination or car every week I am not able to dial car good and reaction times have not been consistent. Last 20 races I bet I have not drove same car, same combination 3 times total.

So to answer your question a BBC is not out of the question but I think it would take longer for me to get the combination dialed in and harder on parts. Now maybe a better option would have been a 632 BBC NA with carb and restrictor plate but I am past that and not starting over there since I already got the crank,rods, pistons etc. Plus so many say that a large BBC NA will not work good on alcohol so I decided not to go that direction.

How heavy is the car? Don't you think that 565 BBC could put you in your target index NA? I would imagine if you can do that, on Methanol, it would be easy on parts, and you could get a handle on dialing it rather quickly.

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Originally posted by Curly1:
markemark, I agree with you but I also saw a significant horsepower loss on one of my motors when I changed from gas carb to alcohol carb. That motor had good air / fuel ratio and timing was good yet on dyno it went 40 Hp down. Of course I will try both on this new motor. Fuel injection may get more of the horsepower back.

Flame suit is on. I have only seen 1 alky carb that worked and it was a one off Frankenstein carb. Huge body with even larger butterflies than seen today. It was a homegrown thing with a manifold to match. I asked how he figured it out and he said that he just measured all the passages. etc and made them larger.

The gas will run better crowd always seems to come from those that have never messed with alky or regurgitate magazines and pit wisdom.

My take on your dilemma is to go with what you know and worked with the last few years.

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Originally posted by Dave Koehler:

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Originally posted by Curly1:
markemark, I agree with you but I also saw a significant horsepower loss on one of my motors when I changed from gas carb to alcohol carb. That motor had good air / fuel ratio and timing was good yet on dyno it went 40 Hp down. Of course I will try both on this new motor. Fuel injection may get more of the horsepower back.

Flame suit is on. I have only seen 1 alky carb that worked and it was a one off Frankenstein carb. Huge body with even larger butterflies than seen today. It was a homegrown thing with a manifold to match. I asked how he figured it out and he said that he just measured all the passages. etc and made them larger.

The gas will run better crowd always seems to come from those that have never messed with alky or regurgitate magazines and pit wisdom.

My take on your dilemma is to go with what you know and worked with the last few years.

Dave, Good points and my gut says you are right. I have a single four intake and several gas and alcohol carbs to try but I also have a tunnel ram and Enderle hat injection on alcohol I will try and I think it may may end up being the way to go.

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Originally posted by FootbrakeJim:
How heavy is the car? Don't you think that 565 BBC could put you in your target index NA? I would imagine if you can do that, on Methanol, it would be easy on parts, and you could get a handle on dialing it rather quickly.

I have already got all the parts for this motor except gaskets. Too late to change set up and I would want better heads, more compression, different cam etc to run it NA. I have a friend with similar set up, Enderle hat on alcohol 598 and his car is lighter and he can not run number.

I never understood spending a bunch of money on the best parts and then corking the engine with a single 4 barrel.

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Originally posted by Dave Koehler:
I never understood spending a bunch of money on the best parts and then corking the engine with a single 4 barrel.

You are right from my experience, made significantly more power with injection. Still I took the advice of several people who are good with the SB2 motors and will try gas. More I think about it alcohol injection should be better on this one. We will see, Few days on Dyno will tell.

Got mine already to test this weekend, suppose to be 72 and sunny at XRP on Sunday.
This is the same 565 and same Rons Terminator I ran in the past so tune up should be spot on. Only thing really different is I am feeding a 1.5 gallon front surge tank from the rear cell.
Truck ran 5.31 last spring with a 1050 Get'M gas carb. A couple of little tune up tidbits, when I put the gas carb on I had to change timing from 34* to 40* and plug gap from.025 to .035 to get it to run descent Any guesses on what it will run back on alky injection?

This message has been edited. Last edited by: Big Steve,

Big Steve, I would like to know how much it picks up. I would guess .10-.15

Did you have the carb on long enough to make enough jetting and timing changes for max performance? The MFI is a proven system you’re returning to. My guess is whatever MFI reduces 60’ time by, double that amount and that’s how much faster it’ll be in 1/8 mile.

Big Steve, I would say that a 1050 gas carb for that 565 was way too small to so the MFI may really help.

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I would say that a 1050 gas carb for that 565 was way too small to so the MFI may really help.

What size is the Rons Terminator? The great thing about MFI/ EFI, you can way oversize the throttle body and not reduce the engine performance.

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Originally posted by markemark:

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I would say that a 1050 gas carb for that 565 was way too small to so the MFI may really help.

What size is the Rons Terminator? The great thing about MFI/ EFI, you can way oversize the throttle body and not reduce the engine performance.

Plus with a carb it requires some vacuum and air flow to draw the fuel through system. MFI basically has no vacuum and you add all the fuel the motor needs. The motor draws in as much air as it possibly can with no restriction. A carb may have .5 to .12? vacuum wide open which is a small restriction in air. So to me the potential for more power is with MFI and in my experience it has been true.

A carb does have some advantages, it is easier to start motor, pretty much self adjusts to weather conditions and is easy to work on. One of main reasons I want to try some carbs is because they are easy to use a restrictor plate to slow down and run number. I am going to change carbs, manifolds, injection and throw everything at it on the Dyno and determine then.

The 1050 was spec out by Joe Jolly at SPE and Trevor Wiggins at Get'M carbs based on my combo. Pretty sure between the 2 of them they have quite a bit of experience choosing the proper carb size of an engine.
Terminator is a 2100 with 0-1/2 twin gear billet pump
2 biggest things I didnt like about the gas carb is the price of race gas is stupid high and the amount of heat the engine builds while running. I could cool it pretty quick when it was off but as soon as it was started the temp climbed rapidly. If you look at that nose it is sealed up pretty tight so no place for the heat to go unless you take the hood off.

This message has been edited. Last edited by: Big Steve,

quote:

Originally posted by Big Steve:
The 1050 was spec out by Joe Jolly at SPE and Trevor Wiggins at Get'M carbs based on my combo. Pretty sure between the 2 of them they have quite a bit of experience choosing the proper carb size of an engine.

Best for what you’re doing and best for absolute performance will influence their recommendations.