Methanol vrs. Gas and Air Speed

mike fabish · Post by **mike fabish** » Thu Mar 16, 2006 10:26 am

With regard to the discussions on air speeds and choke points, would the use of Methanol vrs. Gas slow down the air speed because of the increas in wet flow. I'm asking because our motor on the dyno seem to use a lot of air and yet top end power isn't real high. We have 598" BBC with
Dart/Olds heads 14 degree done by CFE on gas, single dominator. The motor dynos @ 1055 hp at 7400. Our 565" with the same heads manifold and carb dynoed @1040. The 4.500 stroke picked up torque vrs. the 4.25
but not much HP. I do not have flow numbers,CFE doesn't like to provide them. Different cams have been tried but not much changes. In. 2.420"
Ex. 1.880. On the track the 2020 4-link dragster runs low 7.30's @ 180/182 with wing. Any comments would be appreciated. I have a feeling that the air speed is too high and the motor "stalls" above 7300rpm
Could the Methanol change the choke point? Mike Fabish.

MadBill · Post by **MadBill** » Thu Mar 16, 2006 5:57 pm

Since no one that knows has jumped in yet, let me say I don't; but I have heard that alcohol vapors displace considerable air volume and thus demand larger ports. Perhaps one way to tell if the ports are a bit small would be to try running alcohol. If gains are small, that could suport the hypothesis.

Post by **maxracesoftware** » Thu Mar 16, 2006 7:53 pm

We have 598" BBC with
Dart/Olds heads 14 degree done by CFE on gas, single dominator. The motor dynos @ 1055 hp at 7400. Our 565" with the same heads manifold and carb dynoed @1040. The 4.500 stroke picked up torque vrs. the 4.25
but not much HP

1055 HP w/1-4 Carb is pretty good

a 598 cid @ 7400 needs
1569 Carb CFM @ 1.5"Hg to "see" about 1.0" Hg plenum vacuum
and have a chance at making 123 Ve

the (1) Carb is probably too much restriction
with a too high plenum vacuum "Hg ?
to make great top-end HP

even the 565 CID @ 7400 RPM needs approx => 1482 CFM @ 1.5"

to fully take advantage of switching over to Methanol
you will have to go to (2) 4's
as Methanol will immediately cause an 8 to 12 % LOSS in Ve
...using only (1)4 on an Engine that size will result in gains to low-to-midrange TQ/HP , and an even greater loss in Hi-RPM HP.

if you are able to get your hands on a "real" 1569 CFM Carb on Gasoline
..then, with Methanol , that 1569 CFM will now have to be 1726 CFM with Methanol to adequately feed that engine at 7400 RPM...
that's why i recommend the (2) 4 Barrells w/Sheetmetal Intake or
use the Dart Tunnel-Ram intake is an excellent choice w/Methanol

(1.5"Hg / 1.0" Hg) ^ .5 = 1.225

Carb_CFM = 598CID * 7400 RPM * .000289352 * 1.225

Carb_CFM = 1569 CFM @ 1.5" Hg on Race Gas for 598cid

if you see too much plenum vacuum above 1.0" Hg thats the beginnings
of a restriction..you would never like to see 1.5" Hg of Plenum Vacuum

Methanol makes that situation worse..as you instantly loose
about 150 CFM in carb size and 8-12 percent Ve LOSS
in every engine i've ever back-to-back on my Dyno
-----------------------------------------------------------------------------------

for a comparison,
BELLE ROSE, La. - Results of final, round 6 eliminations in TCI/Comp Cams Top Dragster at the NHRA Lucas Oil Drag Racing Series, South Central Division, event at No Problem Raceway:

Car#-Driver(Opp'nt)-RT-----ET-- Speed-----Car#-Driver(Opp'nt)-RT-----ET-- Speed
482A Thomas Levatino 4955 Timmy Graves
E6 ****WINNER**** 0.025 7.286 178.42 0.036 7.314 182.70
T/D Dial: 7.20 (+/-): 0.086 T/D Dial: 7.21 (+/-): 0.104
Prior rounds:
E5 (Andrew LeBlanc ) 0.017 7.238 0.028

Andrew's 548 engine made 899 HP @ 7100 RPM and 736 TQ on my Dyno
in a 1760 Lbs Dragster he ran 7.238 ET and as fast as 7.15 ET
that weekend....Andrew ported his own heads using a vacuum cleaner
and Audie's FlowQuick..they were Edelbrock Victor Race 26 deg Heads

running your Dyno Numbers thru ET_Analyst simulation
a 598cid @7400 RPM w/1050 HP at 2020 Lbs
should run 7.244 ET "if" at that same DragStrip as Andrew,
so it looks like your Dyno Numbers are accurate,
its probably not enough Carb + Intake Manifold
to satisfy CFE's Heads ?

SWR · Post by **SWR** » Fri Mar 17, 2006 5:37 am

OT,sorry: Larry,is your inbox full or something? Tried PM'ing you about a week ago and it just sits there in my outbox..

Post by **maxracesoftware** » Fri Mar 17, 2006 2:04 pm

SWR wrote:OT,sorry: Larry,is your inbox full or something? Tried PM'ing you about a week ago and it just sits there in my outbox..

i just checked..it was 96%..deleted a few..now its 80% full
you might try again or just email

maxracesoftware@yahoo.com

mike fabish · Post by **mike fabish** » Sat Mar 18, 2006 2:07 pm

Larry, Thank you for the valuable information and help. It appears that we're running out of air. We have tried several larger carbs, 1150 and 1250 but there was not much change in the dyno numbers . Would a cam change have to be incorporated with the carb changes to maximize power? and see an e.t. improvement? Thanks again for you insight, and BRAIN Power. Mike.

Post by **maxracesoftware** » Sat Mar 18, 2006 3:39 pm

mike fabish wrote:Larry, Thank you for the valuable information and help. It appears that we're running out of air. We have tried several larger carbs, 1150 and 1250 but there was not much change in the dyno numbers . Would a cam change have to be incorporated with the carb changes to maximize power? and see an e.t. improvement? Thanks again for you insight, and BRAIN Power. Mike.

you didn't Post all the Cam specs you've tried
also which Intake Manifold are you using ?

Your Carb sizes are not enough CFM for 598cid,
but i was thinking more along the lines of the Intake Manifold.
just the Intake Manifold design can gain you a lot of HP/TQ,
so a combo of Intake Manifold + Cam + Carb(s) can make significant
gains over what you now have.....if the Carb not making much
of a difference, Intake Manifold is probably a Cork along with maybe Cam,
but 1150 to 1250 is not a lot of difference when Engine really wants
1500+ CFM....and if you went to a proper Length/Size SheetMetal Intake
w/(2)-4's , i'm pretty sure you would gain Torque/HP.

your 598
1055 HP / 598 CID = 1.764 HP/CID Ratio not too bad Single-4

(1240 HP - 1055 = 185 HP potential gain)
1240 HP / 598 CID = 2.074 HP/CID Ratio for (2) 9375 1050 Stock Carbs
on epoxied extended runner length Dart Tunnel-Ram Intake
Cam Motion Roller
284/314 116 Centers installed anywhere from 114 to 116 CL
1.020/.980 Lift
Dart 14 deg Heads 2.500/1.850

taking out some of the Lift and Duration will hurt HP.
that's probably much more Lift than you would like to Run

if you like the Single 4-Barrell instead...1055 HP is pretty good
out of 598 CID...how much more HP are you looking for ??

i don't think we've ever made more than 1100 HP out of 1-4 Carb
on an Engine size like yours....once we go over 565 cid or so,
i like Tunnel-Ram or SheetMetal Intake w/(2)-4's
as its easier to make significant Torque/HP gains over 1-4

mike fabish · Post by **mike fabish** » Mon Mar 20, 2006 3:57 pm

Hi Larry, Thanks for responding back again. We are looking to produce 1100 HP or more The intake is a Dart single plane spread port, it was port matched by CFE and has some minor appearing plenum work and the Cams were from R/M. First cam 284/298 112 .475 IN .450 ex with 1.8 Rockers. Second cam 288/308 114 .475 and .460. We also tried a cam nearly equal to the first cam except it had less lift. That cam designer felt he could improve velocity with less lift. As I previously posted the power numbers did not seem to change much. I had suspected the intake as being a part of the problem because it was "common" to all three dyno sessions. The cam example you provided: Would that apply to a single carb or was that directed to two carbs? Given how tough it is to make significant power gains with a single carb at these HP levels it looks like a tunnel ram with two 4v-s is the solution. Would an additional .100" in lift help? I'm not opposed to the 2
4v's but it represents a lot of changes to our racecar, and will be costly in both dollars and conversion time. Thanks again for your help. Mike.