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I am looking to build a pro street, and or sportsman chevelle. I want to build the chassis for 8.5 and slower 1/4 mile, I plan on putting an LS twin turbo BBC in it. I have never modified a frame or built for racing before.
I am looking for suggestions on: Tire size, gear ratio, suspension recommendations, ladder bar or 4 link?
Any ideas will be greatly appreciated and considered
Thanks!!!
I would decide just what you want to build. Will it be used as a weekend warrior with trips down the track as well as going to a cruise? Also if you have never done any frame modifications, then I highly recommend getting someone reputable to do the work. You do not want to have a car capable of 150mph+ with someone who has no idea what they are doing let alone welding.
Check out sites like racingjunk, you can buy a rig already done a lot cheaper than you can build it!
Yes, if any frame work needs done it will go to a speed shop. But it will be used for the track primarily, I will also want to be able to drive it on the street. I have been researching tubochargers and you can crank a lot of numbers out with turbo's and still keep a car driveable.
First off, welcome to CHR! I just wanted to let you know up front that you're talking a mega-buck project, especially if you're going to have to hire the chassis work done. Quite easy to get $15K +++ wrapped up in just the chassis by the time it's a roller. I suppose you're thinking an LS engine? With EFI, the rest of the electronics package, a short block stout enough to stand up to twin turbo's and heads with enough capacity to make it all work going to be a $20K +++ engine and electronics package!!!!!
Are you considering a full tube chassis or just a back half on the Chevelle frame? Places like S&W race cars offer both back half and full frame packages for the car, saves a lot of engineering and tube bending time! As Mike mentioned, lots of good roller's for sale on Racing Junk at less then half of what it takes to build one. With a bit of searching you can find the right car that's already certified, too!
If you have really deep pockets, it will be a fun car..... Just didn't want to see you start on it thinking you could get the car done and going fast for any reasonable amount of money!!!!!!
Tyler, welcome to CHR! All three of the guys are giving you good advice based on a lot of experience. Spending a sponsor's dollars is one thing, but taking on a scratch build that's done to meet certification is not going to be cheap, especially if you expect to be competitive! The old speed shop sign has been repeated in about every area of motor sports and remains very true today:Quote:
Speed costs money. How fast do you want to go??
Start with the rule book on what you need for the speed range certification----------many items have a time limit such as belts, harnesses, parachutes,bell housings, etc---------
If your looking at 8.50 area, you should look at 4 link because ladder bars are too limited and bind too much------
Thank you Dave, Yes I plan plan on building an LS motor and I am well aware of the potential costs of building a car like this. As far as chassis building, the main thing that I am concerned with is any frame modifications. I do know a few people that would help adjusting ladder bars or a 4 link depending on what I use but any welding on the frame will be done by a speed shop.
I was kinda hoping I can use the factory box frame with a back half. I have seen a few complete back half kits with all suspension included, I am just trying to figure out what combination of parts and pieces to use.
Welcome to CHR, Tyler -
Sounds like the pros above have already covered the one major factor, i.e., you need a very big bucket of money. When I first saw your post I ball parked $35-50K without bating an eye. I laud your enthusiasm and wish you well in this project. Listen to Jerry - he's built a lot of very fast and always competitive cars over his career. His expertise is legendary. If Pat McCarthy chimes in on motor build you'll be doubly blessed as he's built ton's of big blocks and knows how to not only make them go fast but last a long time as well.
The one thing that's hard to quantify is your desire to see the project through to completion. Time and hard work need to coordinate with smart decisions - knowing what you can do and what's best to have done.
Good luck and keep us informed as the project develops! We love to see a plan come together and will be your cheer leading squad.
Regards,
Glenn
I am just finishing up a c10 restomod that I've dropped nearly 35k into and that was a frame off. Most of the parts used in that restoration were primarily stock parts or just an upgraded version, (tubular control arms, drum to disc conversion etc) and SBC making 481 hp and 496 ft lbs. at the flywheel. point is I have never had to worry about building a car that will be inspected for speed as well as safety.
All I am trying to figure out are suggestions and recommendations on building the chassis specifically. I just wanted to know what works for people running at high 8's and low 9's. I am not really focusing on a motor at this time but I have an idea of how much power I want to shoot for I want to start from the ground and build up.
My first idea was back half, fab 9 inch with 4:11 gears, double adjustable coil overs, 4 link for the rear
You will probably need to run a more stout rear gear.....more like 4:88 or 5:13..........for HP you are looking at the 600-700 range I would think to run 9's.
even with an LS twin turbo? I can see being in the low 1000's for hp. Would a steeper gear work better for that much power and top end speed? 8-9 sec 1/4 car should do 140+
Rule book or you won't get on the track---------------------
Keep it light weight----------to do this in a vehicle that starts out as a production vehicle-----------will take some effort as not only do you need to handle the acceleration but carry the weight---------you will probably need to set the engine back some--probably behind the spindles-------firewall/floorboards--------to run 8s, you will need some tires-----so most likely a welded rear chassis kit with 4 links and coil overs to graph in would be a starting point plus a fabbed front section to mount engine/trans giving room to service package and suspension/cooling---rear wheel tubs
I was thinking fiberglass front clip and doors, and aluminum floor. what size of tire and gear ratio would be recommended?
And I assume QA1 coil overs are the recommended
Who would you go through looking for a front section?
Thank you soo much, I am more or less just getting ideas and researching right now but I wanted to know how others do it and what was successful for them
I really need to get that sign haha
Quote:
Originally Posted by rspears
QA1 are street rod coilovers and not even close to being the best for a drag car....AFCO's or Koni's are the way to go if you want a shock that actually works!!!! You aren't even close to picking gear ratio's or tire sizes yet, don't let the cart drag the horse around! Gears and tires are decided by the engine you're running, the RPM you want to turn the engine to keep the power up, what transmission you're running and a myriad of other things!
What "front section" are you referring to, body panels or suspension?
I guess what would be recommended for a pro street car? Something that could be used for drag week etc.
I don't know if your familiar with Larry Larson's Chevy II. I am looking to build something very similar to that just not quite to that extreme.
Thanks Dave.
Larson's car is an all out, full tube chassis drag car that can and does do a great job on the street! Like the Lutz cars and the rest of them they are very mega-buck purpose built cars....
"The look" can come from spending less money, just realize up front that the level of performance these cars attain and still participate in drag week and other such events is a 6 figure undertaking!!!! Us common folk have to settle for a little less--a car with a back half chassis, LS and a supercharger, nitrous, or a single turbo can consistently and (somewhat) reliably run in the mid 9's and still maintain some semblance of street manners... I'm doing a rebuild on a friends car right now that has a long history of street and some drag performance. Once it had a 632" BBC with a 2 stage nitrous system and went a best of 7.90...now it will be a mild mannered 540" BBC and a single shot (max of 200) nitrous and probably do low to mid 10's and be "competitive" even in street trim---though somewhat slower.... The car is a '69 Cutlass, same as your Chevelle (other then some sheet metal) and if you're willing to do the work and spend the $$$$$ you could expect the same... Be warned, though!!!! The Cutlass is just a rebuild, most all the good parts were already there before. I'm doing the car for only enough to cover materials and utilities but even at that the bill is well in excess of $10K not counting the engine and driveline!!!! If I still had my big shop and was paying my help and overhead the bill would be at least double that.....
You're probably already tired of me stressing the money involved in this kind of build. Reason is I've seen far too many people come into a project like this all fired up, then run out of $$$$$, time, patience and often all of the above when the project is about half done!!!!! Anybody can go fast, just depends on how fast you can afford to go!!! My first best advice would be too set up a budget of how much you can REALISTICALLY afford to spend on the project, and what kind of time frame you're looking at from start to completion! Also, there are two definite rules that apply to a Pro Street, Drag Car, Street Rod, Restoration or any other kind of build:
1. It's going to take longer then you thought.
2. It's going to cost more then you thought.
With that in mind, it's time for you to set up some realistic plans for the car and figure out a budget for it, IE $XXXX dollars for the chassis, $XXXX dollars for the engine, $XXXX dollars for the driveline, and $XXXX dollars for paint, interior, and cosmetics.....
Just some advice from a guy that's been playing these games for way too many years!!!!!!!
Alright maybe Larson's chevy wasn't the best example but what I'm looking at on his car is how he set his suspension up for the street but also being able to handle his launch at the line. I am not wanting to go all out as he did but I would like to build a step or two down from that. Such as I would like to stay away from the tubular chassis.
As far as starting this and not being able to finish it; it's more than just money to me.. Working on cars and learning what you can do with them is much more than a hobby to me, it is something I can come home from work and be excited to work on. That's why I call it a project, I have no time limit as to when I want it finished nor the total expense. I will however work on it tell it's done, I really don't like starting things and not finishing them.
A project like this I do not plan on sparing any expense; I want to build a car completely and I don't want anything done and have to wonder if it will hold up.
The most critical part of any build project is planning the build, first at an overview level, and then getting down to details about what you want in order to get it to the end. Once you have a plan in place, the next most important part is following you plan, and not heading off down rabbit trails that end up driving you to make major changes to work already done, or spending 10X what you planned in a given area. Planning your work, then working your plan gets you to a satisfying end result. Having an unlimited budget and no fixed end date should make planning a lot easier.
Ok, here's some pics of the Cutlass. It's a back-halved car with a 10 point cage, front suspension is stock other then light weight springs and Koni drag shocks. The frame is stock GM from the ladder bar crossmember forward, rear frame is 2" X 3" rectangular tubing. Wheel tubs, trunk floor, interior panels are built from 20 ga. The back is a Dana 60 differential with ladder bars, coil overs, and a panhard bar. The dash, gauge cluster, and console are custom built.
Is this something along the lines of what you're contemplating??????
Dave was 100% on target when he said ...It's going to take longer then you thought.... It's going to cost more than you thought. I could buy a new car off the lot for what I have invested to date, & as you can see there's still a long way to go.
I'm not ready to throw in the towel just yet, but I can tell you Kids, Grandkids, Other projects & just life in general tend to get in the way of the best laid plans from time to time.
Here's a few random shots from my Photobucket Archives of the stalled build.
http://img.photobucket.com/albums/v2...age12305sm.jpg
http://img.photobucket.com/albums/v2...aro2-15-06.jpg
http://img.photobucket.com/albums/v2...edaluminum.jpg
http://img.photobucket.com/albums/v2...Rollerback.jpg
http://img.photobucket.com/albums/v2...h4-26-08-1.jpg
http://img.photobucket.com/albums/v2...28/flange9.jpg
http://img.photobucket.com/albums/v2...8/7b86465e.jpg
http://img.photobucket.com/albums/v2...8/a295844e.jpg
http://img.photobucket.com/albums/v2...8/0114fbba.jpg
http://img.photobucket.com/albums/v2...llFlanges1.jpg
http://img.photobucket.com/albums/v2...Flangebore.jpg
http://img.photobucket.com/albums/v2..._Panorama1.jpg
http://img.photobucket.com/albums/v2...inletwell4.jpg
http://img.photobucket.com/albums/v2...assSideFW1.jpg
http://img.photobucket.com/albums/v2...iptmock-up.jpg
http://img.photobucket.com/albums/v2...10firewall.jpg
http://img.photobucket.com/albums/v2...roproject2.jpg
http://img.photobucket.com/albums/v2...z28/PROZ70.jpg
http://img.photobucket.com/albums/v2...rorear53sm.jpg
Dave, That cutlass is very similar to what I am wanting to build. What is the potential completion plan for that car? Street strip?
For a car to be certified to run 8.5 and slower do you need a 25.x cert chassis?
And Pro70 that looks like an awesome project, Looks like you have came a long way on it. I am also very glad you're not giving up as well, gives me more and more hope. What is the time a car like that is certified for?
Thanks!!
The Cutlass is moving into "semi-retirement" and will be just a street cruizer. Long story behind the car.... Depends on where you're running, but yes the correct answer is to say the car has to be certified by NHRA to run 8.50's. Some tracks have an inspection day prior to the season starting to get the car certified. Pro Z went through the whole procedure on his 'maro and posted it on his build thread. If you check on the NHRA web site it has the information on how to get the build information and criteria that the car must meet to be certified for different ET's....
Alright I am having a hell of a time finding build requirements for ET's. All I found on there was a quick reference chart saying yes or no for different areas. All it says is for a 7.50-9.99 second car it needs: driveshaft loop, NHRA chassis sticker, roll cage but it doesn't say if there are any other chassis requirements for 8.50-9.99.
I did find else where in the book that a 10 pt cage with swing out door bars are permitted for 8.5 and slower. But I will double check with NHRA to make sure nothing on the chassis needs to be added.
But aside from that, setting up the car its self... I am just trying to get some ideas and amounts on paper. For the chassis I was thinking:
-26" rear frame section
- Double adjustable ladder bars (still unsure if I should use ladder or 4-link)
- diagonal link
- Double adjustable coil overs in the rear (unsure of a brand)
- drive shaft loop
- springs (unsure of spring rate)
- fab narrowed 9 inch
For the rear
Something like that sound reasonable?
You need to order the entire SFI spec sheet from NHRA, or find someone who has it.. A car the size and weight of a Chevelle need a 4" or 5" stroke shock, which for me makes AFCO the shock of choice. AFCO's can also me mounted inverted, which lowers unsprung weight. I've also used Koni's and Strange, all good shocks. A four link would be the preferred suspension, though a quality ladder bar setup works equally well on the track in a car like this. If you're going to be on the street, then I'd suggest a Watt's linkage instead of the diagonal link. Don't worry about spring rates now, you need the car put together and put on a set of scales to figure out the correct rate. When you decide what coilover to run, you'll want to build or buy a solid link in the coilover's position, set at ride height, to have in the car while you build. What you do need to have before you start setting frame rail width and height is the tire and wheel combination you'll be running, this eliminates all the calculating and guessing on where and at what height things should be...
If you can get a Moroso CompetitionEngineering Catoloque there is a lot of info in the back of it about different types of suspension and all the way thru specific packages for certain cars---------
I will definitely get a hold of one of those then. I am a little rusty on racing suspension Jerry so I am taking as many resources as I can!
How do I decide what tire size to run? I know in someone else's post Dave actually commented on something saying people make the biggest mistake putting too large of tires on a car when they don't need them. However, a car that I am working towards building will be a street car, and a lot more power hitting the tires so I assume I'll need a little larger tires to compensate for the higher hp. Just looking around at other cars similar to what I'm shooting for I am seeing anywhere from 29" tall through 31" tall and 15" wide through 19" running either 4:11 or 4:88 for the rear. I know picking a tire size will somewhat determine what gear ratio will be used. But what bases your tire size?
Tyler, for a street/strip car I'd say that your tire height is going to be driven more by appearance than anything else, and then you may have a set wheels & tires for competition. To get into the quick times you're targeting I expect that you're going to end up with some very tall rear gears, so you might want to consider a Gear Vendors OD unit to give you some street manners. Your cruise rpm is affected by your tire diameter, rear gear ratio, and final tranny drive (OD) ratio. Once you have your basics set you can make a couple of test runs to see where you are going through the traps, and maybe use your competition tire diameter as the final variable to dial in your gear/rpm to optimum.
yes, so the bigger the tire the higher the RPM will have to run to turn the bigger tires. But the gear vendors OD has been an idea depending on tire size and gearing.
I was planning on a built TH400 as far as a tranny, The motor itself will hopefully just be a beefed up LS BBC with twin turbo to keep it streetable. But how do you decide a base front and rear tire?
Once I figure tire size I suppose that will tell me how narrow to go with the axle, frame, and if I need to get drop spindles or springs.
I've got to ask, what the heck is an LS BBC??? If you're doing a Pro Street car, rear tires are going to be around 15" wide, 30.0" to 31.5" tall. You'll also have to decide on ride height and the car's stance...
just a fuel injected aluminum big block chevy, I guess that's always how it was referred to me as.
So really width doesn't play a huge roll in deciding. But if I went 31 x 16.5 rear and 28 x 7.5 front it would give my a little room for suspension travel correct? I think chevelle's ride fairly level with stock suspension maybe a slight rake.
An LS and a BBC are two different engines, ok, you're going to be running a big block Chevy. Tire sizes will work on a Chevelle, on a build like this you're not stuck with the stock ride height or rake, you can build it into the car as part of the build.....
Here's a link to a rear frame section at S&W Race Cars. They build some very nice pieces, used to be a dealer for them and built more then a few cars from their packages. Study the site, they have rear frame sections, cages, suspension, and most everything you're going to be needing......
http://www.swracecars.com/store/Dire...OSCAR_441.aspx
Oh.. I'm sorry about that, I guess I was just thinking of a LS series big block--
So are those sizes reasonable? I'm not saying I can't adjust ride height or rake without using the tires but I'm still wanting to drive it on the street so I don't want to go overly low with it. I assume the size mainly is being used as a reference point to figure rear housing length and frame rail width.
Im really glad you're still trying to help, I feel soo out of the loop compared to you and the others on here.
I have been looking on there at their rear frame kits actually, would you use one of those or a section set up already for a ladder bar or 4 link? Such as: 64-72 Chevelle 2x3 Ladder Bar, 64-72 Chevelle, FRAME 64-72 CHEVELLE & 70-72 MONTE CARLO - FULLY WELDED Race Car, Racing, Dragster, Chassis, Roll bars, Cages, Fabrication, Suspensions, Parts, Shocks, Springs, Motor Plates, Brakes, Drivelines, Housings
They are a little more spendy but they are complete and ready to weld on.
Personally, with all the really great technology available for the LS engines and their EFI system, I'd forget about using a big block.... An LS can be built to 427 + cubic inch, and the electronic controls of both fuel and timing are light years ahead of the big block stuff and for a lot less $$$$$ too.... Weight and cost are both less with an LS, horsepower is plenty for and 8.50 car. At last year's LS shootout, there was a ton of them in the high 7 low 8 range and not near the mega bucks you're talking with an aluminum BBC and an EFI system for it.....
Yes, tire size and wheel backspacing is the first thing to have as an absolute when you start a build. Don't feel like some kind of dummy either!!! Lots of us on here have been doing this stuff for 40+ years and we sure as heck didn't know it all when we built our first projects!!!!! As the old saying goes, dumb questions are a whole lot better then dumb mistakes!!!!!
Thanks a lot Dave!
I did do some research on the same similar set up on a small block using twin turbos etc; and its roughly 25-40% cheaper to get really similar power. I am still unsure but I am kinda leaning towards small block.
As far as the chassis goes I am going to get some measurements off the car so I know how much room under it side to side I have before I decide on anything. I have a pretty good idea on what it is but I want to double check =)
there were ls bbc engines LS 5 LS 6 over the counter LS7 along before the LS sbc i built both parts for the ls sbc is going to be more or on some things the same to build the BBC as for the ls sbc is lite years ahead of the bbc that is a big No. you are better with the LS small block over the older small block chevys as for heads but the bottom end with the ls the older chevy is abit more user freindly thats is why World makes a old sbc block that the new top half of the LS bolts on to it and Dart has reworked a new LS block to be better then the stock one .as for big power threw the stock Gm ls block the alum one moves around alot in the main webs and piston bores. new Gm ls7 sbc block are not cheap $2880 or about thats dealer cost i would not put alot of power threw it about 600hp on the Gm block . for the same price a Big M iron block can take over 2000HP and with billet cap 2000HP for about the same cost or less the cost of a LS power level will have alot to do with cost of build do not kid your self them low 8s lsx or ls base engine s have money in them .you could go on the yellow bullet as see how many are going fast with stock parts some on there have gone that fast with junk yard bottom ends they say.. i yet to find a good LS core for $250