This is a discussion on Cube Question within the Internal Engine forums, part of the LSx Technical Help Section category; I feel that this sounds like a silly question but if I'm buying a short block and the prices for ...
06-09-2008, 03:49 PM #1
- Join Date
- Dec 2005
- Sanford, FL
- 98 SS
I feel that this sounds like a silly question but if I'm buying a short block and the prices for anything over a stock Ls1 are the same, are there any Cons to going biggest? Texas Speed offers the 364, 383, 402, and 414 for virtually the same price. (There is also an iron block 408 but I'm scared of the weight difference since my car is my track toy for road racing...not drag). It seems to me that more cubes can allow for the engine to make more torque down low and so I don't need to run at as high an RPM on the track which in turn might even be more reliable (is that bad reasoning?) As you can tell I'm trying to talk myself into the 414. What do you guys think? thanks for all your help.
06-09-2008, 08:19 PM #2
once you go oversquare in your bore to stroke relationship there are cons to having to travel that long of a stroke. A very long stroke relults in increased side loading on your piston and rod combo resulting in lower rpm capability due to increased rotational mass and decreased durability in the long run. I dont think a 414 would be to bad at all. Generally I think they say anything over 427 C.I. on a gen III starts to max out the ideal bore vs. stroke relationship. Caus they have monster gen III's that are like 454's and even bigger. That 414 should be a torque monster and the stroke shouldnt be to radical cause it's using the big bore block. Shit i'd do it bro, i'd even run a 427 but I like to drag race alot. Im putting in a stock bore and stroke 6.0 block right now 364 CI. Id love to stroke it over 400 ci if I could afford maybe in future when its ready to be rebuilt but right now its very fresh engine. Good luck hope that helps you. Smaller stroke engine will still rev a little quicker but like you said with all that torque you wont have to rev to the moon you will be making good flat power all the way through and like they say there is no replacement for displacement.
Last edited by BlwnCamaro; 06-09-2008 at 09:41 PM.
06-13-2008, 02:48 PM #3
There is no such thing as bore to stroke ratio, Maybe you were thinking Rod to stroke ratio.Idealy you want 1.75:1 and some pro stock guys run as high as 2.0:1. And i have build motors with less then 1.5:1.
The BIGGER THE BORE the more H.p. the engine will make,not just because of more inches,but things like unshrouding the valve,because the cylinder wall is not as close to that side of the valve, better flame travel,becasuse there is more room.
The longer the rod the more Torque it will make, becauce of lever action, the longer the lever the easier something is to move.
As far a long stroke, piston speed it what you should be talking about.
Piston speed for different strokes and RMP's
3.622(ls1) @ 7000 = 4229 Inches per min.
3.622 @ 7500 = 4531 IPM
3.750 @ 7000 = 4375 IPM
4.00 @ 7000 = 4666 IPM
3.250 @ 9400 = 5091 IPM(MY RACE MOTOR)
4.500 @ 7200 = 5400 IPM(Most big blocks)
5.5625 @ 8000 = 7416 IPM(812cuin Pro Stock0
So as you can see piston speed in the ls1 is very low.
Rod to stroke
6.100(ls1) 3.622 = 1.68 ratio
6.125 3.622 = 1.69
6.125 3.750 = 1.63
6.125 4.000 = 1.53
6.250 4.000 = 1.56
So as you can see Bigger is Always better.
They is no replacement for displacement.
06-13-2008, 03:03 PM #4
what i never said bore to stroke ratio. You must not know what you are talking about. I said relationship and it does exist. Its when you go oversquare in an engine that means that your stroke is longer than your bore size. I wasnt discouraging large bore size I was referring to extremely long stroke. For example If you have a 4inch bore and a longer than 4 inch stroke the motor is considered oversquare. And bigger is not always better it depends on what you plan on doing with the engine and what your application is. It's a fact that a longer stroke decreases rpm capability and side loads piston more. Furthermore this guy autox's so his application is different than drag racing, because he would see extended high rpm's and an extremely long stroke is not designed for that. In my post I said 414 would be fine on an lsx with big bores, its when you go much over a 427 with lsx that your bore to stroke relationship can go oversquare and a long stroke is not designed for road racing. You should do more research before you come off saying things dont exist to certified mechanics. Not trying to be a jerk, I was trying to give old boy some helpful insight and it is facts not unfounded opinion or speculation.
Last edited by BlwnCamaro; 06-13-2008 at 03:05 PM.
06-13-2008, 03:07 PM #5
i remember that show different strokes or was it something else...........there is a replacement for displacement........a turbo makes you go from zero to hero
06-13-2008, 03:17 PM #6
06-14-2008, 02:15 PM #7
A 4.0 inch stroke is not a long stroke.And a 4.0" stroke will travel the same distance in a 3.0" bore or a 5.0" bore(piston speed).My point is that if you can aford it a 4.0" stroke motor is going to make more torque(better to get off the coner). And in a hyd. roller cam motor, the valve springs and are going to be the rpm limiter not the 4.0" stroke.
Hunderds of people on this site alone put 4.0" cranks in ls1 blocks(over sq.)
A 4.0" stroke in a 3.9 bore is not going to cause you any problems.
Shit for that matter i would have NO PROBLEM putting a 4.250" crank even a 4.5 incher in a stock bore ls1,The problem is, i (and most people) just dont have the money for the machine work it takes.
Certifed Mechanic? You work at the dealer?
Do more research? LOL!!!!
I take a lot of pride in what i do, and it shows in my work.That is way i'm able to work for myslef and be successful.
I have had my hands on some of the fastest cars in the country,and do lots of work for many of the best engine and chasiss builders around.
I don't mean to start a pissing contest.
I have been doing this for over 25 years,started going to the track when i was a little kid,i have forgot more about engine that most people know.
Buy the biggest engine you can afford, you will not regreat it!!!!!!!
The only way bigger is not better better is if you are looking for gas milage.
06-14-2008, 07:57 PM #8
Last edited by BlwnCamaro; 06-14-2008 at 08:07 PM.
06-14-2008, 08:46 PM #9
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- Thornton, CO
Red Tint Jewelcoat
- 2008 Trailblazer SS
06-14-2008, 10:02 PM #10
assuming the turbos are the same on equal boost the larger displacement of course..............but a 346 turbo is hard to see coming.......thats a whole different subject though
06-14-2008, 10:15 PM #11
- Join Date
- Aug 2005
- Thornton, CO
Red Tint Jewelcoat
- 2008 Trailblazer SS
TTi kit (screw a twin kit, waste of money) is OUTSTANDING!!
The APS twin kit is nice, but I would personally prefer the single TTi kit with a T80 or larger depending on cubes.
UNLESS there is a need to keep ALL your stock locations for accesories. Then the APS kit is very nice.2008 Trailblazer SS
Yank PTB3600, Kooks 1 7/8" LT's, 4" intake, E-fans, Magnaflow, Sonnax kit, tranny cooler, tune.
Lowered, HID's, tinted.
1999 Pontiac Trans Am WS.6 #1747 SOLD
531.1 RWHP 481.3 FT/Pounds all motor.
06-15-2008, 05:10 AM #12
06-15-2008, 10:19 AM #13
After all of that talking the only point you have made that bigger is better no matter what. There are a lot of people that think like that and "your" theory was already proven wrong a long time ago and was shared by most old schoolers a long time ago before you were even born. You are 30 and have been working on cars for 25 years! Uh Yea LOL!
I prefer not to make this into a nonsense thread so i'll keep it as simple as possible. So seriously lets weigh out what is actually being compared here.
Thread starter asked if there were any drawbacks to going with a very large LSX bore and stroke combo for "ROADRACING" "AUTOCROSS" not dragracing.
The engine sees very demanding high rpm's for extended periods so it is a different engine application than drag racing which sees short bursts and has totally different dynamics and requirments. Like I said I drag race and will stuff the biggest C.I. under my hood I can and agree with you in some senses there.
I was trying to give the thread starter an Idea of the finer pros and cons against long stroke big bore combo vs. moderate stroke bore combo in regards to the application of ROADRACING.
I build engines application specific because that works better than just applying one theory to all builds and assuming that just because it runs and works it the best way to do it. By your bigger is better opinion I guess that means the biggest cam is always best too right, NOT TRUE it depends on application like I am saying in regard to bore and stroke and i'll tell you why:
1. It is simple physics, long stroke big bore combos have a heavier rotating assembly, this mass is harder to control at high rmp's and results in quicker wear on bearings and bottom end under extended high rpm conditions as compared to lighter assembly. Stay with me im talking precision here, the difference between the engine staying together for even a little longer in long race conditions. The type of approach that the best in world use to win races.
2. More physics, the farther an object swings or travels from a centerline the more enertia in builds and takes more energy to return to centerline. So if you are swingin your pistons out there further (and they are heavier) on a long stroke it causes bottom end to wear faster in the long run than shorter stroke counterpart engine which benefits from less rotational mass and enertia. All translating into increased bearing life.
3. Furthermore like I stated earlier long stroke side loads piston more because of offset of crank to achieve long stroke.
4. A long stroke motor has higher piston speeds at a given rpm than shorter stroke counterpart. Higher piston speeds build more heat in the cylinder walls and cause parts to wear faster in the long run because of increased duty cycle at given rpm, very simple.
5. You are saying a cam is only limiting factor to rpm??? That is not true, a lighter rotating assembly with smaller pistons and shorter stroke will always rev faster and quicker due to less rotational mass and enertia. Think about it is it a coinincidence that the 600 engine in my sportbike revs to 16K rpms, no its very small pistons and rotating assembly. Different application but the same principal applies to cars. Lighter rotating assembly=Less wear and tear on components and higher rpm potential. Common knowledge in professional engine building community.
6. Roadracing engines need every advantage they can get for durability anything you can do to design in features to your engine that will help it specifically for the application will help success. How refined do you think the approach is for guys that win championships. Their team looks at every single angle they can to get an edge. You can always be better, just cause you have been doing something a certain way doesnt mean it cant get better. If your engine lasting for a certain time period than great, but what if it could have lasted longer if you had attention to detail. I'd rather keep improving and pushing the envelope with advanced engine theory and technology and research rather than going off old theory of bigger is always better. I love stroker motor, but it is not ideal to have a extremely long stroke on a roadrace engine and even a drag engine will last longer with a little more conservative approach in regards to matter.
There are limitation and reprecussions to every change you make, if you gain something somewhere there is a chain reaction somewhere else where you may be losing a different element. Every engine has its sweet spot combo balance of power and durability and I believe should be designed application specific to get the most out of it. It depends on what your needs are.
I actually even know way more info on this subject but im trying to keep it simple. If you think that bigger is better for every application provide some solid facts that counter the facts and physics I have presented here. The guy is road racing not drag racing. Bigger is not always better.
Last edited by BlwnCamaro; 06-15-2008 at 11:01 AM.
06-15-2008, 10:35 AM #14
Not trying to start any more disputes, but his durability and reliability would be slightly less for roadracing with Forced Induction because of so much extra heat especially at extended high rpms and power demand. Plus having more parts to break. Definately would be more reliable all motor for autox or roadrace in the long run. Just my .02 cents.
06-15-2008, 10:40 AM #15
Plus to thread starter as I stated in earlier post 414 LSX would probably strike a good balance between pros and cons, just trying to give an idea of differences and benefits. Like stated its if someone goes a whole lot bigger than that especially in your autox application, some of the drawbacks will be clearly evident in the long run durability department as compared to the lighter rotating assembly. People that have a lot of experience in that application will confirm what I am saying, they dont run extreme long stroke engine, thats a drag race combo.
Also the old schoolers could have never imagined running this many cubic inches in a small block cause it didnt exist, so why use old thinking. The LSX is a totally different animal than the older engines the bearing size in a smallblock LSX and the components can only handle so much weight and enertia as the engine is producing way more power and C.I. than originally designed for, believe me there is a limitation to going to big on these smallblocks. They are pushing past big block type C.I. with smaller components and eventually you will stress combo out. There has been a lot of research based on this idea in the search of building the biggest LSX engine. The introducion of the aftermarket blocks has pushed this envelope even further. The guys setting Quarter Mile Records currently have to tear down there combo after just a run or two many time to replace head gaskest and failed components, thats how far they are pushing the envelope using forced induction. There is definately a limit to when you start to comprimise durability.
Last edited by BlwnCamaro; 06-15-2008 at 10:52 AM.
06-15-2008, 10:56 AM #16
Not trying to be abrasive guys, I was simply trying to give old boy some sound comparisons on the finer points of pros and cons until I was called out. I try to respect everyones experience on here but that was uncalled for by 99transamC/FIA, this is a help thread. Oh yea I didnt mean any disrespect to old schoolers at all, its just an analogy, but to highlight how things have changed over the years. I love sbc and started off with that and still love em but injected, computer controlled, LSX motors have more technology and complexity so to me its a more precise approach to set up right and takes more research to improve on.
Last edited by BlwnCamaro; 06-15-2008 at 11:09 AM.
06-15-2008, 01:29 PM #17
- Join Date
- Dec 2005
- Sanford, FL
- 98 SS
I really appreciate all of the advise. I don't even mind the argumentative nature of some of these replies It sounds like the bottom line is that going with the larger C.I. will be perfectly fine in my road racing (30 minute high RPM runs) simply at the expense of bearing life.
Rob, do you know what the weight difference between your iron lung of an engine and the aluminum block is? I know I could just call them to ask. Thanks again everyone. Money will be the guide in this tour just like everyone else.
06-16-2008, 11:54 AM #18
That is great info.
For someone with nothing to prove you sure spend a lot of time trying to prove yourslef.
We are not talking about 450+ inch small blocks.
In the past putting anything even close to making something over sq. was alot of work(to short of a deck). Therefor leaving no room for a long enough Rod to increase the rod angle creating large amounts of piston side loading.With the ls1 being a tall deck you can run a long rod greatly reducing side load on your piston.
Yes the cam is the limiting factor.Limiting factor not how fast it revs.There is a big difference in rate of accell and rpm limiter. No bigger cams are not the answer.With a hyd. cam you will never see the limits of the 4" stroke.
todays parts are way better,including bearing materials, allowing you to run this "long stroke" 4.0" strokes with no problems.I build many oval track and road race motors, and don't think for a second, if the rules allowed 450+ cuin, that long stroke apps would be in every car on the track.I know big bore short stroke motors make more horsepower,all i race is big bore stuff.(336cu incher @ 9600 rpm 3.250 stroke)
And for cm2papa ,save your money on the big bore and put your money in the heads,and intake.Put a 4" crank in a stock LS1 block and you will not be disapointted.You will find WAY more power in the top end leaving you motor over sq. and very,very relieable.Plus you wont have to rev it as high!
Not that it matters, but for you turbo guys, a turbocharger is a way of incressing the amount of air "displaced" by the engine. therefor bigger is again better.
Last edited by 99transamC/FIA; 06-16-2008 at 03:07 PM.
06-16-2008, 12:24 PM #19
taking about bore to stroke
Take a ls1 put a 4.0" crank in it with a 6.125 rod
And then take a ls1 put a 4.0" crank with a 6.25 rod.
Which will run better?
Both have the same "bore to stroke" Ratio(.975)What is perfect?No number i have ever seen.
But the rod to stroke ratio (which is way more important and determines side loading) changes from1.531 to 1.562.
The bigger is better was a statement was about a 402 or 414.The question he asked.
Last edited by 99transamC/FIA; 06-16-2008 at 03:15 PM.
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