steve2001sh

Everyone goes through the phase of adding up all the advertised "HP gains" from part manufacturers and convincing themselves that they can have a 600 HP car from $1000 of bolt-ons. Then you read around a bit and realize nothing is that easy or that cheap. Eventually, you have to realize that you may not ever have a 9 sec car that a couple of models are constantly sitting on.

So, this post is to try to get a good plan for people with more modest goals. Anyone with real experience with car building (like you've done it before), please post what you think the cheapest way to take a stock LS1 F-body to 400, 500, and 600 RWHP (No NOS).

Example: A new air lid gets you around 10HP for around $100. That's $10/HP, so that will probably be the first thing anyone wants to do.

stangkiller2005

iTrader: (15)

well heres how i see it...

you start with the lid, and catback, than you get headers,ory, and cutout... than you start lookin into other stuff. pully, ls6 intake if you dont already have it. or a lsx fast intake. ported TB, ported maff... there are alot of things.. than you look for a nice big heads, and cam package. the bigger you go the more hp you will get down. also a good dyno tune will help the numbers rise. if you really want to get into spending money. you can either stroke that motor. or bring up the cubes with a 400, 408 or something along those lines. without nitrous i see it kinda hard to see 500+ on a budget.. cuz it does get really expensive.. but with full bolt ons and a nice big heads and cam package...you can be very close to 500+

o and also alot of suspension upgrades will help greatly get the power to the wheels... and when u get that high in power a 12 bolt will be ur new best friend

steve2001sh

Sure, bolt ons are typically done first. Lets try to be more specific though. Say things like "The loudmouth catback gives you 15HP for $300, so that's $20/HP". Also, I am looking for total numbers like "I think you could get 400HP for about $2000" or "I think you could get 500HP for about $6000". My point is to help show people how much they can realisticly expect to get on their budget, be it low or high and then which parts are best for their goals. Forged pistons are great, but if you only want a 400HP car, they are probably a waste of money. Similarly, we know not all headers are created equal. If you want 400HP, you should get $300 headers because they are a good $/HP value. If you want 600HP, you may have to get $1000 headers even though the $/HP isn't as good, because you really need to squeeze every last bit out of them.

EugThinks

I think the XXXhp for $X,XXX is possible and probably a good guide, but listing out individual parts with their costs and gains is a little problematic for someone looking for a budget build... different combinations of parts make different amounts of power. What I mean is that it isn't simple addition when it comes to gains from mods. The other way of listing it, along with different example combinations, sounds like the more useful list.

The problem here is that there aren't really simple answers for this kind of thing, because there's a lot more to the end result of modding a car than the peak HP numbers... I'm assuming your target audience isn't looking to just build dyno queens. Especially once you get past basic bolt-ons, different choices will also affect the torque curve/powerband, driveability, etc... and then there are non-hp mods like tires, suspension, and wheels, which are all also essential in a decent build, even a lower-power build.

However, it sounds like you're probably experienced enough to know all that, and are just trying to find an easy way to pass on knowledge to less-experienced car people... I'll leave actual numbers to members who know more than I do. Just please make sure you also pass on that the simple list is not nearly the whole picture.

steve2001sh

That's very true. Anyone reading this post should be aware that it will be oversimplified by its nature. The idea is to give new people a general idea of what they're in for and a good path to start out on until they learn more.

Combinations will affect gains in ways that probably only experienced engine builders can quantify, so I hope that some wonder onto this post.

HP is not everything, but lets face it; that's where most people start (and some end). Power under the curve is a better measure, but it is harder to measure. When upgrading power, strength parts will be necessary, so that should be factored in. Handling and acceleration will not be covered by this post (because its already a very broad question).

silverTA2002

iTrader: (1)

Plus, there are plenty of mods that a worthwhile, but get you no HP.

Clutch, gears, rearend, short shifter (manual)

stall, gears (auto)

Suspension work, sub frames, sticky tires, etc.

In terms of individual HP quotes you see online.

Take the best #'s you've seen, then multiply by 50% to get a realistic idea.

If every car started with 325rwhp stock, and lid gave you 10hp, catback 15hp, headers 40hp, tune 20hp, intake 20hp, MAF 15hp, ported throttlebody 10hp, pullies 5hp.......

That's 460 rwhp with just bolt ons!!!!

(oh wait, that's impossible)

Starting to catch on??

98_Formula

iTrader: (15)

this is a good idea, as when i first bougt my car i was looking thru catalogs and lookin at advertised numbers just like a noob should! sure i had my 500hp bolt on car all mapped out... lmao... then i got onto this site. It might also be a good idea, maybe here or in a different thread, give a general idea of what it would take to hit 12's, 11's, 10's, 9's, etc at teh track... becuz like some people said, non horsepower mods like tires, gears, clutch, Stall converter, etc can have a huge impact on how your car runs...

marcdez

iTrader: (2)

Free mods first, Lid and filter, catback and cut out, headers and y pipe, Cam and springs, TB and LS6 intake, and last would be the tune. If you buy used parts and install them yourself you could probably get there close to 2000 dollars. If you buy new and get a mechanic it could be expensive. There are good guys that will install the cam and springs. I got mine installed for 300 thats the only mod I didnt do myself and the tune I havent done that yet.

Hoss Ghoul

iTrader: (2)

Use the search, read the dyno section, read the 12 and 11 second sections. Then price their mods.

That's how you will really find out what XXX HP costs.

300bhp/ton

But you can't do this as it's impossible.

You can only quote what a mod will achieve over stock. This is because it's not a fixed increase.

All you can do is guide people on which route they won't to go but you can not list out all the items, espcially different manufacturers of the same item such as exhausts.

If you plan on a turbo setup then most of the bolt on's are NOT the way to go and would be a waste of money to buy them. Same applies to many supercharger setups but with a slightly different component list.

Example:

With a turbo setup you do not need a lid, headers, TB, intake manifold, air filter and so on yet you can still easily make 400+ rwhp.

Most people go for bolt on's because they are comparitivly cheap per mod and can be done one at a time where as serious setups require heavy work in one hit and a lot of initial out lay in terms of money.

If you want 400rwhp you will generally need a minimal of:
-induction/exhaust mods (i.e. Bolt on's)
-large cam
-tune

450rwhp:
-as above
-heads

500rwhp+:
-Forced Induction or n/a large displacement

Alot more than 500rwhp:
-Built block with power adder

Going back to bolt on's and their gain. There is such a term as "diminishing gains". Essentially there is only so much bhp you can 'free' up with bolt on mods. So this means the more mods you do the less HP each mod thereafter acheives compared to performing the mod on a stock engine.

Personally from what I've seen 350-360rwhp is about all you can get from a stock internal LS1 in terms of bolt ons, this places you at 400-415bhp.

As for cost/hp again it depends as you can buy coated headers for half the price of stainless ones but they will see similar HP gains, so which one do you quote?

steve2001sh

hmmm.... yep, this is going badly.

I can only use dyno numbers from members to go so far, though I am starting to think that would be my best bet anyway. You see, a person with a 400 HP car posting dyno numbers may be attempting to build a 500 HP car, so they would be using different parts than someone who was done.

One of the primary points of the post is this. There are tons of arguements out there of "is this worth it?", but that question always depends on your goals. I'll give an example. Are Kooks longtube headers better than Hookers longtubes? Most people agree they are, but are they worth 3x the $$$? That depends on how serious you are. If you intend to stop at 400 HP, then don't waste money. You don't need the best.

I think I will search the dynos and post some examples.

300bhp/ton

You seem to be confusing yourself.

Any well designed long tube header will make similar HP gains. The biggest difference in header prices is due to material and not HP potential.

All of the cheap headers are mild steel, some available with optional coating. The expensive headers are made from stainlees steel, which generally looks better and will certainly last longer due to it's anti-corrosive properties.

It has nothing to do with HP.

Plus dyno sheets prove little in the long run as each car responds differently under different circumstances (altitude, atmospheric condidtions, tyre pressures, etc.).

Also there are different dyno types out there which derive HP in different ways and thusly have different HP numbers. Most common in the USA are Dynojets, these are inertia dyno's as opposed to brake dyno's such as Mustang Dyno's. However there are many other makes/types out there.

But to show an example of HP differences a car making 400rwhp on a Dynojet is more likely making ~374rwhp on a Mustang Dyno. This is soley due to how the dyno's work.

You then have the added complication of different correction factors and standards such as SAE. These correct to specific atmospheric conditions but are not always used or used correctly. Graph smoothing is anohter often mis-used tool on a dyno which can easily show far higher PEAK numbers than what the car was really acheiving.

Aiming for specific HP outputs is not the way to mod a car unless you are a 'dyno Queen'. Street/track performance is a much better measure.

You can easily reduce ET's at the track without the need for any additional HP at all.

The best way to optimise spending in terms of HP increase is research and understand what each mod does and why.

For example,

A rip off mod is the smooth bellows from SLP. It is only a small tube which runs in a straight line for about 3". The smooth bellows isn't even smooth as it has a bulge in it. Any increase in airflow is minimal at best and it won't help in the HP department. For visual appearance you could argue that it's worth $5-10 but that's about it's lot. No way is it worth $50

Exhaust headers - why do people change them? Well if you don't know then you run the risk of buying the wrong ones.

Exhaust tuning is about two things, flow and more importantly scavenging. Stock manifolds actually flow pretty well, espcially on a n/a (naturally aspirated) engine. But they do not scavenge. Scavenging is the introduction of a 5th cylce into the combustion process where one exhaust pulse creates negative pressure in another cylinder which helps to draw intake air into the conbustion chamber of that cylinder. In order for this to work the exhaust pule must enter the collector at the correct time that the exhaust valves are open on another cylinder.

Shorty headers don't work very well because the primary pipes are too short and the pulse does not end up in the collector at the correct time. In order for them to be efficent you would need to the engine to rev much higher (I have heard reports of 10,000rpm plus). So shorty headers do not scavenge on an LS1 engine combine this with the fact that they don't flow much better than stock items on a n/a engine is the reason people don't see much in the way of HP gains with them.

Mid length headers suffer the same problem, but some wild cam setups will probably work well and produce good PEAK numbers, but at lower rpm's the same issue as with shorties will exist.

Long tube headers are the best bet for a n/a engine as they will make the most power/torque across the entire rpm range and should make good/best PEAK numbers also.

If you plan on a forced induction setup (turbo or supercharger) then things change. This is because this 5th cycle becomes eliminated. This is due to the fact that the intake air is being forced into the engine above standard atmospheric pressure. So scavenging is far less important (or redundant) with FI setups, the most important factor is flow. And all tubular headers (shorties, mids, LT's) do out flow stock cast items. So if FI is you plan then shorties will work as well as LT's do.

This website has a lot of very very good info, check out the stickies and use the search function if you are still uncertain then always post up and ask.

But IMO research is the key, as sadly there are many badly modded motors out there. Some don't perform much better than stock and many perform worse.

There's a link to a mod guide in my sig have a read and see if it helps. If you still have questions post up or shoot me a PM.

steve2001sh

Similar, yes, but my point is to determine whether you are serious enough to spend the extra money to get very little in gains, such as with ceremic coating (that is if you believe it produces more HP at all). Many people would do just fine with the cheaper ones.

I intend to try to make my comparison somewhat valid, though not scientific. For starters, I will only look at dynojet numbers. I understand there will be other variations, but I'm only trying to provide a general estimate.

The point is not to aim for a specific HP, but to show a good way to get to each level and the price involved. I am not using ETs, because those will matter less to the autocross people. I'm not including things like transmission or suspension, because the topic I'm trying to cover is complicated enough to start with.

This is not exactly true. That "5th" cycle is to replace the last bit of exhaust with clean air. A 10:1 350 ci engine will displace 350 ci per cycle (2 rotations). If you manage to replace 100% of the displacement with clean air, that is what we refer to as a VE of 100. The trick with scavenging is that 35 ci of exhaust left sitting in the heads. If you can manage to get that out too, it would be like having a 385 ci engine. Additionally, some of the limiting factors of how much boost you can run are heat and turbulance. If you have a restricting intake and exhaust, your turbo will have to work harder to cram all that air in there, thus heating it, making it more turbulant, and reducing the max boost you can run without detonation.

300bhp/ton

We are evidently at cross purposes however I still do not beleive you can lay down that this mod produces this much power for this price as it's never that black and white and will only lead to cause more confusion.

As for coated headers, well I don't understand you point as it seems reversed you say spend more for coated as you believe it lends to more HP yet most of the high end headers are not coated

If my understanding of scavenging is incorrect then I apologise but I really don't think it's about making an engine's displacement bigger than it actually is (your example of a 350ci engine becoming a 385ci) as the physical dimensions will not change and the only way to force more air into an engine is via forced induction which uses compression and scavenging does not compress.

In the sticky in the external engine forum it states that scavenging can contribute up to 80% of the air intake velocity into the combustion chamber.

Also on a stock engine I really don't think a SLP LM will yeild 15rwhp, maybe nearer 5rwhp.

However if you had a cammed LS1 with LT's and ORY still running thru the stock catback then yes the SLP LM could well be worth 15rwhp under those conditions.

1998silverbird

iTrader: (29)

228Cam or bigger, valve springs, headers, ory, cat back, lid,ported TB,and a tune..

steve2001sh

A stock cylinder has about 48 ci (381 ci / 8) of useful space. This includes the 346 ci of displacement (places the piston goes) and the 35 ci in the heads (hence the 10:1 compression).

In a non-scavenged exhuast stroke, the piston will push about 43 ci of exhaust out (if the exhaust is perfectly free flowing). This leaves another 5 ci of exhaust sitting in the header area. Scavenging can suck this last 5 ci out of the header and replace it with clean air if the cam has overlap. This is how it is "like" making your engine 10% bigger. It just makes use of the space that where the piston can't go.

silverTA2002

iTrader: (1)

Is this correct?

I know it's not true when comparing bolt on gains on a stock (internally) motor vs. a modified one. For example, long tube headers on a stock car might gain 15hp, but on a heads/cam car could gain 30hp. (I know this isn't what you're comparing, but still).


What you're saying is that a catback might gain 10hp on a stock car. And a lid might gain 10hp on a stock car.

But, a lid and catback would only gain 17hp together? (numbers just estimates for comparisons sake).

I thought the reverse was true. That a lid = 5hp, catback = 5hp, but lid + catback = 12hp.

Anyone?

EugThinks

300bhp/ton is right in general, silverTA2002... it really depends on what specific mods you're talking about. Two mods that affect different and mostly unrelated parts of a car's functionality might get an addition total, and two mods that do different effects but help each other out will probably do better with each other than they would individually, but most often (especially with bolt-ons) the functionality of various mods overlaps, so that multiple mods won't simply add up their individual effects for the total.

Of course, that's a really vague description, since I'm really just a noob at heart, but you get the idea.

300bhp/ton

That's it exactly.

I mean we all must have sat down at one time or another and generated a list of bolt on's we'd like to get and add up how much advertised HP gain we should see, but the numbers just don't add up.

A typical M6 Fbody should lay down 290-300rwhp SAE on a Mustang Dyno (I use Mustang as it closer represents SAE Net figures quoted by manufacturers).

However the most you are likely to see from a bolt on car is 350-360rwhp so a gain of typically 50bhp.

But when you add up the potential gains something doesn't add up, e.g.

All these numbers I have seen advertised as genuine bhp increases per mod (over stock )
-lid or induction kit = 15rwhp
-headers = 20rwhp
-catback = 12rwhp
-K&N filter = 2rwhp
-Ported TB = 8rwhp
-LS6 intake manifold = 20rwhp
-!CATS = 10rwhp

This short list already totals 87bhp which would mean our car should be making 377-387rwhp way above what people really achieve and we haven't even considered pulleys, electric water pump, lightweight flywheel, lightweight driveshafts and wheels or a tune.

So the only logical conclusion I can think of is that of diminishing returns, however if someone else has an alternative idea I'd love to hear it.

steve2001sh

That's pretty much the idea.

First, it is better to think of mods as a % HP increase. If a mod makes 10 HP on a 300 HP car, it should make 20 HP on a 600 HP car.

Secondly, it depends on how badly you need the mod. A stock exhaust is somewhat restrictive on a stock car. If you get a cat-back, your exhaust will be pretty good, so removing the cats at this point will help a little, but not as much since a lot of the restriction is already gone. On the other hand, If you somehow managed to build a 600 HP car with a stock exhaust (don't ask me how or why) your exhaust would be extremely restrictive. Then if you did a cat back, your gains would be huge.