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Finally in the 11`s


502ci

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Sorry so long getting back, I lost track of this post..

 

On the RPM intake, it is merely a matter of closely matching the head ports and the gaskets and leaving the manifold ports very very close to being a little smaller than the heads. This helps in reducing reversion. The combinations that run an RPM into the 10's are very narrow banded torque curve motors with 106/107 LSA, lots of lift and mild duration (relatively speaking).

 

I use a Victor Jr. right now, that is port and gasket matched to my heads and then carefully aligned front to back once the manifold bolts are in finger tight..Then once aligned I torque it down.

 

If you have a 468 an RPM is worth some testing, I can tell you that the driveability on the street is way better betweent the RPM and VJ.

 

My Car with driver is 3950 pounds as it rolls down the track, weighed it 3 weeks ago and 4 weeks ago at Maple Grove and New England Dragway.

 

May2006launch.jpg

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Here is my timeslip data...

 

My 1.57 60 ft. was a mistake frown or I can`t find that one timeslip, either way it wasn`t on my two 11 second runs.

 

60 ft. ---- 1.640

330 ft. --- 4.853

1/8 ET ---- 7.606

1/8 MPH --- 89.10

1000' ET -- 9.951

1/4 ET ---- 11.959

1/4 MPH --- 112.20

 

The other 11 second was almost exact as above.

 

smile

The low 1.6x 60 foot sounds about right, the 1.57 is in the high 10 area..your incrementals are right in line with only a slightly less than typical mph increase...

 

typically 1.58 x the 1/8 mile = 1/4 mile ET. cars our size and shape Normally aspirated will pick up 23.5 to 25 mph from the 8th to the 1/4...you are at a 23 mph increase..

 

I would try knocking 2 degrees of total timing out of it and trying that. Also look into trying a 1/2 or 1" open spacer.

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Look at MC71454 (tom) as a reference, quessing at a 3500# weight his et would require in the neighborhood of 600hp at the wheels and 650/675 at the fly wheel depending on the drivetrain losses. Thats 1.2/1.25 Hp per cube, thats good for a homebuilt combo.

 

Not belittling anyone here, Tom is a master tuner, he has tweaked and tuned just about everthing he could get from his combo. Tuning ability is a must on any combo, if you can't tune it then it won't perform to it's best capability!

 

Don

Don,

 

Thanks for the kudo's on the the tuning. However, master tuner is a bit of a stretch..LOL..

 

what I think you may need to understand is that my motor and combination is far from optimized...and is anemic in a few areas.

 

It is:

 

1. Under carbed

2. Under cammed by .100" in lift - both intake and exhaust, yes 0.100"

3. Under cammed by 10 to 12 degrees in int dur

4. Under cammed by 8 to 10 degrees in ex dur

5. Under geared

6 Under convertered

7. Weighs 3950 pounds at race weight with driver

 

I now have heads that can support more cam, I now have heads that need more carb and will need even more carb when I change the cam to match the heads. Once I change the cam I will change the converter and then I can change the gear to help with the cam on the lower RPM end and to have enough RPM on the top end to take advantage of the heads and the cam....etc...

 

Until I upgraded my heads in 2006, my combination was Designed to run easy 11.00's in a Street Legal Class in 2004 and to be the fastest car in the class. I had to slow it down from 10.70's to 11.0's. It worked out pretty well as I ended up second in Points (Due to the my second broken transmission that summer with the second one in the last week of points. But I went to the NHRA bracket Finals as top qualifier in DOT class since I was first in points the weeks before.

 

So my set of parameters is completely intentional, planned, and above all realized.

 

The class has been changed to an 11.50 cutoff and I am not competing with the car in that class frown . So what the heck let's methodically improve the combination...One could call it tuning, but not in the sense that one may picture like setting the timing or adjusting the idle mixture.

 

I believe you can get so much more knowledge and satisfaction by moving your ET and MPH quicker and quicker by improving your combination as you go and that is the approach I have been taking with this car. I think many of us here do that.

 

Does this sound familiar to anyone ???

 

"13's and then I'll stop...well I think I would like to go 12's..maybe then 11's in a couple of years and it never ends for some of us. smile Some people like to go for it all in the first shot and that's OK too. Having a motor built and a combination designed to handle 1.5+ HP per CI normally aspirated lends itself to streetability, durability, and maintenance issues that many don't have the time or resources to contend with.

 

I assure you I could build a motor that approaches 1.5 hp per CI in my back garage but that wouldn't suit my needs for what I do with this car right now, (emphasize the right now)plus it's so dam heavy I would get tired of replacing drivetrain parts in the short term...LOL....

 

 

My car started out in the 14's and it has been a great experience and wealth of knowledge earned.

 

Anyway, nothing argumentive intended just thought I needed to add a little background to what I have done and why..

 

Have a good one...

 

Tom

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Tom, I do fully understand that you are not (component) wise maxed out. Thats why I stated that you have tuned the combo of parts you now have to the point of it's ability. Any more big gains would require parts changes to the combo.

Don

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Tom, I do fully understand that you are not (component) wise maxed out. Thats why I stated that you have tuned the combo of parts you now have to the point of it's ability. Any more big gains would require parts changes to the combo.

Don

Thanks Don,

 

I figured you probably knew that, I wrote most of that for others to read who may be just starting out or thinking of some significant performance upgrades..

 

The importance of tuning your combo is so often overlooked and too many people just throw parts at their cars and hope for the best...

 

Thanks for the post..

 

Tom

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Ok, I'll ask a stupid question:

When you put together a combo and try to select all the matching components to make the combo perform....where do you start? I mean do you choose a cam and build around it, or start with a compression ratio, a set of heads, or somewhere else?

I have an existing combo that is stil in its experimental stages and has been for 4 years. I know it has unrealized potential but I'm not sure how to coax it out. Cubic money isn't an option, I'm hoping that there is some logical path to follow.

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I'm curious as to where in the NHRA rule book it talks about at what ET/MPH requires what type of safety equipment and can I view that information online? I'm not sure, but I thought that at 12.99, or better a roll cage came into play? I'm also curious as to what the 1/8 mile conversion would be to require the same safety equipment and how much IHRA rules differ from NHRA? Thanks.

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Wallaby, I start by asking/listening to the customers expectations and what they expect for drivability. Then I look at chassis and rear gear, trans and converter, CI customer has as a basis. This all factors into the choice of head, intake and compression. Then one must account for the exhaust system to be used. Once I have a head chosen and prepped I look at the flow #'s, pick/design my cam lobes and LSA and ICL to be used. At this point I have a very good idea of the powerband is. The last piece is the carb based on the needs of the combo. This is the way I approach each build to get the best match of parts and the best possible power I can.

Don

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Greg, The rules aern't on the NHRA site only the revisions. I have been told that it now reads that a 5 point system is good from 11.49 to 9.99 after which a cage is required.

Don

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maybe they'll change that to 9.5 for a cage, I hope

eek

 

laugh

 

I new it, gonna go for the 9`s, looks like you will have to baby it on several practice runs...then let her rip on the final run that will get you warned slow down or else. lol

 

That will be my plan any how... nutz

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I'm not looking for the 9's, think they are going to find me weather I like it or not, I hope I come up a little shy, I have to find consistancy

9's in a non tubbed heavy car and your looking for consistancy with out major suspension mods.... I don't know about that but good luck with it besides it will be fun for you to hit the 9's regardless......

kneelsuckers.gif

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Wallaby,

 

Very Good question, nothing stupid about it. I agree with Don as in you really must set a realistic goal whether it is stop light to stop light a specific ET or MPH at the track or just a reliable cruiser that you'll just break the tires loose a few times.

 

Let's just consider street/strip combinations so there are a few Fixed items that will come into play such as exhaust that Don mentioned and a cruising RPM is in the picture early as well. A combination built for specifics can be accomplished many ways it is just the matter of the owners or customers realistic preferences. So the up front Realistic expectations are critical.

 

Right off the bat you have exhaust and rear gear and tire size, these seem to be the most popular Fixed elements behind motor size. So after these items are decided you can get to work on what internal parts, carb, intake, converter, etc. will reach your goal.

 

Can you expand on your entire combination it's performance and what your goal or goals are ???

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I don't want to hijack this post, I thought I'd just throw a question out while all the "know-it-alls" were here bench racing. It has been very interesting to listen in.

My engine has something that isn't right about it: I don't know what it is. In the past when I had something that needed an expert to look at, I had a great guy to take it to but in the last year he has retired and closed for good. It seems that everyone else wants to tune the car by following the directions on the underhood sticker!

I have a 468 with 9.25:1, iron oval port merlin heads and a Comp 268XEH. I had my HEI recurved and just instaled a stage II Q-jet from Carb Shop. I still have the stock intake and exhaust manifolds, and a stock converter. I was hoping I could build a combo that would have big torque numbers, and reach it's peak at my cruise rpm for mileage potential. (3.31 gear, 26"tire).

It seems to run pretty strong when it's wide-open, but cruise and idle seem difficult lately. This new carb is running much richer than the old one I was running, and to be honest the throttle response was much better with the old lean jetted carb. I just don't know what other adjustments I can make so this new carb will make my engine happy. Right now I have 17 degrees inital timing with about 36 total. Still I'm idling smooth at about 600, but only 15 inches vacuum. Full throttle seems ok, but it feels as if it's laboring otherwise.

A couple of years ago I had this combo on the dyno, and it said 365 RWHP. I was depressed because it was exactly what the sticker on my air cleaner said it would be.

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I guess I did a great job of killing the discussion.

I think if I have time this weekend I might open up the engine and verify that my camshaft isn't going flat or something. I was hoping that this engine would be just "chomping at the bit" and would instantly react with added throttle, (it's not too responsive unless a lot of throttle is used) but maybe the cam is too big or lobe seperation too close or something?

From my description above, does anyone see a major fault? Why would my engine feel sluggish with a "proper" fuel mixture of 12-13:1 ?

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that fuel ratio works for under power, but for cruising, it's to rich, 14.7:1 is the perfect ratio for cruising, 12-13 for power, try changing metering rods (bigger ones) for the part throttle, this will lean it out, 15" of vacuum isn't bad at idle with that cam, the last time I had mine running, I had 6" at idle, wonder what I'll have with the new one, going to use a vacuum pump for the brakes this time

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Whoa!

I really didn't want to tear into this new carb...it was supposed to be dialed in already for a performance street application. When it first arrived it was so bad I couldn't even get it to idle and it surged real bad up to about 40mph. That was enough for me and I sent it right back to them.

The second time around they had more than enough information about the intended use: right down to tire dia, cam specs, etc, etc. They sent the same carb back to me with no explanation as to what they found wrong or how they fixed it. When I called them on the phone they said they changed the power piston and the float level and now it "is dialed in to cruise at 12-13 to 1, and it pulled real hard on the dyno".

I pulled it open tonight to find they also had changed the rods & jets. It was setup with a 76 jet and a 44 rod. Their original receipt said different.

Anyway the rich end seemed ok, so I worked on leaning out the cruise setting with a larger rod. I used what I had on hand and installed a 50 rod and HOLLY CRAP! It made the cruise a little TOO lean, but the improvement was like night & day! The throttle response is incredible now and it pulls very strong at WOT. Maybe a size or two smaller on the rod and I'll have it dialed in.

Suddenly the topic on drag tires is pertinent. smile

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