Tire and gear ratio

[Arekusu]

Hey all -

So my 454 is getting built with the Lunati 60203 cam..oval port heads(290's) I'm trying to decide on tire height to gear ratio.. I know a lot of people are saying wait till you bring it to the track and all but I'm trying to get a rear built and am trying to minimize gear / tire changes.. I did some math and posted it on Chevelle tech.. I got very few responses. TKO-500 transmission 3.27 first gear. What do you guys think?

Transcribed from Team Chevelle

"Ok with 3.42's and a 3.27 first gear that equals 11.1 start line ratio
With 3.55's and a 3.27 first it equals 11.6 SLR
With 3.73's it equals a SLR of 12.19

That didn't take into account tire height. Just rear gear and first gear ratio.

Then this website bumped me to the next part.. which is distance in first gear calculator.. I'm guessing I'll make 500# of torque. Per what I was told earlier in this post. 4100# truck . I'll also use a shift point of 5500 ( maybe too low / too high?)
http://www.5speedtransmissions.com/distancecalc.html

With 3.55's
26.5" tire = 36 feet
27" = 38ft
28"=42ft
29"=47ft
30"=52ft
31"=58ft

With 3.42's
26.5" = 41ft
27"=43ft
28"=48ft
29"=53ft
30"=59ft
31"=65ft

Soo I am by no means a racer. But I would like to have my truck preform well when I decide to bring it to the track ( this is assuming traction actually happens).. or buy expensive tires / gears.. How do I best interpret my results? Am I wanting to try and get to 60 feet in first or hit second before that? What do some of you recommend?"

....End transcription....

I plan on flipping my trailing arms and putting some good bushings in them. QA-1's and springs may also be apart of the plan.

Recommendations? I'm serious. I'm looking for some experience/help on this one so I don't have to do this twice.. gear and tire changes are expensive.

Alex

[BigDan3131]

It boils down to what fits and how much tire clearance you have. Is it lowered quite a bit? Do you intend to drive more on the street or spend more time at the track? Does that trans have OD? What are your cam specs? Like the rpm range of it and lift and duration@ .050? Do you plan to add NOS or turbos?

Honestly I would buy what fits well and fills in the wheel wells and have a second set of rims for the rear just for racing with DOT legal street slicks.

[Arekusu]

Sorry I forgot about the first post

....... transcribed..........


Specs : 454 .030 over (2 bolt mains)
Lunati Cam 60203
cam RPM range: 1800-6200
duration @ .050" 227in 233 ex
110 lobe separation
ISKY lifters.
Rocker Arms: Harland Sharp 1.7
Radiator...? I have a summit racing one right now that I ran with the small block.. should I upgrade? Where should I look?
Water pump: Stewart High flow
heads: oval ports # 3964290
2.06 intake 1.72 exhaust
closed chamber
(would rather not chane the heads if I don't have to)
Pulleys: ? are stock ok, id rather not spend a grand on bilit alum. ones.. and I really dont like the look of them that much. *( where is the best place to get pulleys?)

flat top forged pistons (TRW)
Eagle stock replacment connecting rods with ARP hardwear
Stock crank
Rotating assembly just got balanced.
Hays flywheel, Pioneer harmonic balancer both SFI
Edelbrock preformer RPM intake
Pro systems carb (4150, 950hp main body)
ARP Head bolts and main bolts

-- What I "think" I know--

I need to make somewhere between 420-500 hp to run a 12.5 in the 1/4 and go somewhere near 115mph ( a little extra added in to make up for my loss of traction and hopeful catchup)

Big blocks like compression, and most preformance cams require it. I'm guessing that with a compressed head gasket thickness of .041 I should have somewhere near 9:1 compression? Ill have to do the math though to make sure.

I'm running a TKO 500 5 speed (still street driven, don't want an auto) but I was thinking I should use 3.55, or 3.42 to use more of the big blocks torque band for my cam choice (though it advertises to pull to 6200 rpm), and not loose my 1st gear all the way. TKO-500 gear ratios 3.27,1.97,1.34,1.00,.68

Tire size - I was thinking about a 27"- 29'' tire by 10 - 10.5'' wide. Hopefully this will let it hook up? Are stamped steel rims ok to accompolish this? I have some new wheel vintuque rims I'd like to use. Going for more of a classic hot rod look over prostreet.

........end transcription........
So that should help.

Soo I pretty much am going to get a new axle and have it slightly narrowed and have tubs in the back without moding the frame. So I'd like to buy it once with about the right gears and select a good size tire to go with it.

Help is appreciated

[BigDan3131]

Based on a cam close to your specs it should make around 435 hp@5000 rpm and a torque peak of 544ftlbs@2500 rpm. IMO I would go with the 3.55's because if you end up going to a tall tire 28" and taller it will make the 3.55's feel like less gear and with a .68 OD you should still get decent gas mileage.
Stock pulley's are fine, I just upgrade mine to aluminum versions instead of going serpentine. Be sure that radiator you have is tig welded only as brazed wont hold up to the high flow Stewart pumps.
If you were open to a new set of heads you will gain more hp. I tried running your heads in my program with 2.19/1.88 valves and it didn't show much of a change.

[Super73]

Dan, where/how did you come up with a peak TQ of 544@2,500? The question is directed towards that RPM, not the TQ number. Seems a bit early for a peak. But then again I'm not a big block guy.

[Arekusu]

Ok 3.55's and a 28" tire.

Now from my first post the calculator I used said the distance I would travel in first would be 42 feet. From a racing point, should I try and get my gear and tire combo to try and extend to near / past 60 feet? So that way I shift to second close to / after 60 feet? Is that better or am I way off on this idea?

I mean I've lined my truck up on a quarter mile track before and all but I never really tried to bench tune it prior to assembly so I get it right. I'm kinda trying to do that now.

Thanks for the info on the brazed radiator with the Stewart pump.. I would have never known.

Alex

[BigDan3131]

I have researched the newest version of CamQuest 6 and from what I have read its within + or - 5% of the given power outputs. I have also compared my finding with Engine Analyzer Pro 3.9 and they are within that same 5%.

The figures were based on a cam close to that of the Lunati and same engine specs he mentioned.

[68GMCCustom]

I would think you'd want to go with as big a tire as possible...bigger footprint for traction? Not saying its what you need but 30" tall drag radials fit under my step fenders.

[Arekusu]

I really feel peak torque at 2500 is a little early.. On cam quest it shows torque building early but sustaining until about 4500.. thats with a XE268H. I'm not sure how much differently the lunati cam will act.