This is simple... A V-8 makes more bottom-end torque, therefore, lag is less of an issue. Well, less noticable, unless the proper turbo is not chosen.

 

You are correct the spool up rate is very good with a v8. Since the 4.6 isn't that huge of an engine though I have also choosen a bit smaller exhaust housing cause of this and wanting to focus more on spool up than upper end rpm hp and max hp out of the engine. Its all a ballancing act though in the end.

 

Z,

I am curious why you say this. The torque is simply going to depend on the boost pressure and the intake charge temperature (which determines the timing you can run) no?

Turbos can be spun very fast (like a centrifugal supercharger) and thus can generate a TON of boost, but it is usually at a different point in the power curve than with a roots or screw type supercharger.
Although designs have gotten better in recent years, there is still a lot more heat coming out of a turbo than out of a non-centrifugal supercharger. Centrifugal compressors generate a lot more heat than a roots or screw type compressor (which is one of the reasons the ATI kits includes an intercooler). A lot of heat also bleeds through the turbo housing, as well as through simple radiation due to the proximity of the exhaust and intake side of the turbo.

That's not to say that you need an intercooler, just that when you consider how little a turbo weighs, the extra weight of the IC is a small price to pay.
If you are not running an intercooler, then you have to run with less boost and you need to retard the timing. Neither of which is a good idea if you want to have fun
The RPM does not matter. The quantity of exhaust gas is what matters. A V8 is simply moving a lot more air and does not need to rev as high as a 4 to spin up a turbo.
This is just completely wrong. As you already pointed out, the air from the IC goes right into the engine and does not go anywhere near the turbocharger after it is cooled.

I would never take on a project like this myself, but I totally respect the work you are willing to put into it. Good luck!

-Don

 

I'd love to turbo my5.4, but there are a couple of things that would concern me.
1) cast pistons
2) lack of fuel
I don't know about you guys, but that 1/4" fuel line going in and out of the filter doesn't look like it can't come close to supplying enough fuel. Lean is mean.....but dangerous! You'd also need better chip programming, just for starters. Dave C.

 

David,

When you consider the time and money needed to install a turbo, you might want to consider doing what Neal is doing with his engine.

By the end of the year he expects to have a Naturally Aspirated 400 HP 5.4L engine. He is also building* a clean block, strong crank, strong connecting rods, strong pistons and good heads. He has also upgraded is MAF, throttle body, and ported and polished _everything_ on his engine.

*corrected from: "He decided to start with." This just did not come out the way I meant.

The advantadge to this approach is that Neal can bolt on a huge supercharger or turbo and not think twice about it. He knows his engine will be able to handle whatever he throws at it.

As for the fuel system, the bigger problem seems to be the injectors rather than the fuel line (at least initially). The stock injectors are good to something like 305* HP. After that you need to move up to something larger. Many of the people here are running 42lb injectors for example. It goes without saying that any of the changes to the fuel system require a bigger fuel pump as well.

*Corrected from 350. A typo I did not notice.

If I may ask, is there any reason you prefer a turbocharger over a supercharger? I tow and want power at 1k RPM so the supercharger is a better choice for me.

Having said that, my engine is complicated enough without extra oil lines, intercooler tubes, and rerouted exhaust lines running all over the place

 

the biggest problem with the turbo is that no one makes a kit for our trucks, which is to bad because a properly engineered turbo kit would kick the cr@p out of a centrigal or roots s/c. (check out hot rod mag from about 2 months ago, better yet ask any owner of the 231 ci grand nationals if low end was a problem)

the stock pistons and fuel lines will have no problem with a s/c or turbo making 340 to 360 hp.
for a weekends work, about $3500, emmision legal, no head or intake gaskets you cant beat a s/c.
Neal will have over $2000 in heads alone if he is doing the whole engine thing he will have invested at least $5000, he might make 400 hp but the torque of the s/c will not be there, also remeber that with the heads and cams that a looser convertor and gears are probably needed. i have done both n/a with cars, s/c with my truck, with the s/c i bolted on 100 in a day, instant smile

 

I'm not going to get into a SC versus TC debate I am curious, however, why people prefer one over the other, in the end it seems to come down to personal opinion.

As to whether or not a TC would beat a SC depends on just how far you want to go with your engine.

In the end the only thing we are talking about here is boost. You can run more boost with a TC simply because you can spin it just about as fast as you want. But unless you are willing to spend thousands and thousands of dollars for engine modifications, and a _LOT_ of money per gallon for racing fuel, all of that boost doesn't mean a thing.

For the boost levels most people consider reasonable (up to say 15 lbs) there is no inherent advantadge to a TC over a SC.
Neal is not going to be stopping at 400HP. That is simply phase 1. Mike Troyer would like to see Neal make 700HP and considers it easily done. You aren't doing that with stock parts. As to it costing $5k, that would be a significant underestimate in my opinion. From what I have read, a racing crank alone will cost you almost $3k.

It really all depends on what your goals are. I've become more and more interested in building a 600+HP motor recently and if I decide to do it, the supercharger will be my last purchase. (I prefer the simplicity of supercharger installation and what I consider to be a slightly more predictable power curve. Others will undoudbtedly have their own opinions )
Anyone doing an engine buildup and not thinking about the transmission and the rear end is probably crazy anyway

Seriously though, the 4R70 is already maxed out (torque-wise) with the stock engine. Bolt on a supercharger or turbocharger and you are beyond the rating of the tranny.

As for the rear-end, a whole lot of power doesn't do any good with an open differential so that should probably be a consideration anyway.

-Don

 

good luck with your 600 hp project.

neal has had his truck since 99 and he ESTIMATES (thats the key word) 340 hp and high 13. 700 hp is out there and there are maybe 3 to 5 lightnings here that make it (race gas, not daily drivers) only one has broke a srovk crank and it was the fastest one making 20 plus # of boost and spraying no2.
if you are serious about the 600 hp you need to check out the hot rod from about 3 months ago, same motor , same carb al running the same amonut of boost, the results are undeniable i will see if i can find the graphs and post them, (i used to think that the roots dominated low end also)

 

Thanks!
His "estimates" are based on quarter mile times and truck weight making no traction and are probably pretty reasonable. Some people think he is making a lot more horsepower, some (myself included) think he may be making less. Either way it is probably a good ballpark.
20lbs is a good level of boost for a race engine. As for 700 being out there? I don't think so. It is a little over 2 HP per cubic inch which isn't crazy for a race engine.

As for breaking the crank, if you are going to build a race motor, why not just spend the money and put in a good crank as well. There are two things you do not want to do in an engine, one is throw a rod (Although spectacular to watch), the other is break a crank.
carb? This thread was about a 4.6L V8 no?
*Edit: I understand what you meant by this. You were referring to some sort of side by side comparison of a TC and SC on a hotrod with a carb *
I still believe a positive-displacement unit beats a centrifugal unit in the low end. You could make a ceiling fan generate plenty of low end if you wanted to spend enough money to do so For most applications, the roots-type supercharger is a good choice. I prefer a Lysholm compressor because it is a positive displacement unit _and_ a true compressor. As I have said numerous times, everyone has their own preferences.

I also think turbochargers are excellent. I choose not to use a turbo because:
1. My personal experience has been that turbo's simply do not have the low-end of a supercharger, though they are unbeatable up high.
2. My experience has been that the power offered by a supercharger is more predictable than a turbo.
3. I prefer the cleaner look and easier maintenance of a supercharger install over a turbocharger install. (By easier maintenance I mean not having to work around the oil lines, IC tubes and exhaust-intake modifications when I want to change plugs)

My experience with turbochargers has been that they work really well in a high-rpm engine. The 5.4L is simply not such an engine.

These are just my experiences with the various units. Each one has its strengths and its weaknesses. Each one has certain applications where it excels. For my money, the Lysholm is the best all-around unit. As always, different people will have different preferences

-Don

 

i have no doubt that the roots beats the cent. in the low end. just remeber that the roots is probalby harder on the trans and rearend, u joints , axles and tires. neals estimates are from 1/4 mile runs that he did over 2 years ago and has since done more parts and work.
based on what i have seen in the form of dynos and 1/4 mile times on 2v 4.6 mustang,340 h.p. is a tall order, but i have been wrong before. cosidering that lightings go mid 13's with 380, 3.73 and mph at 99 to 101 (mph is the true measure of power, e.t can be your trans, gear and weight.) picking up 80 hp without cams, head work or intake is a tall task.

 

Absolutely. Before my engine goes in the transmission will be replaced with one of Gregg Evans' Monster Boxes. The drive shaft will be replaced by a chro-moly one. The rear end will get lower gears and a girdle (This is a 9.75 which is really stong anyway from what I have read). The cast rims will be replaced with light-weight forged aluminum rims. Traction bars will also go on to reduce rear end movement and help prevent u-joint problems by keeping everything in line.
Both Neal and I have the 5.4 which gives us more room to play.
Every little bit adds up. Polishing the intake and keeping everything clean. Getting rid of unecessary drag like the 13lb radiator fan. Using lighter and smaller tires to reduce rotating mass. Using a lighter drive shaft. Underdrive pulleys. All of these contribute to horsepower gains. Does it constitute 80HP? I do not know. I have already said I think that number is high but you never know.

-Don

 

HI!... WOW! How did I get dragged into this? LOL!

1st off I am still running the bone stock long block that came in my truck from the factory. A "99" 5.4 with 145,000KMS. It still has stock block, rods, pistons, heads and cams. Just bolt ons and some other stuff currently. Currently I'm running the stock 80mm MAF, stock (ported) 70mm TB. The whole trick is to get everything to WORK together that you use.

2ND : If you guys must know, I spent $3100(U.S) for my fully race prepped heads and CROWER stage 2 billet cams, from FOX LAKE/MIKE TROYER.

3RD : Getting good TQ out of a 5.4 is pretty easy in N/A trim. You have to remember that a 5.4 uses a LONG ROD configuration which everyone knows is great for a torquer engine. The "L's" SC'ed 5.4 only make 440FT/lbs of TQ. The superchip alone makes a N/A 5.4 close to 400FT/LBs with that being the only mod. So with the other mods I have, I would have to say that I'm probably pushing around 425FT/LBS of TQ.

4TH : As for this 700H.P engine......... I am going to build another 5.4 soon. I will be using the block that is in my gallery. It will be getting the best of everything, plus a WHIPPLE SC pushing about 24-28PSI, but will probably only make about 600H.P (flywheel).

5TH : As for the 9.75 rearend being almost indestructable..........well..... Last week I just had to spend $1350.00(CAN) to have my 9.75 re-built. I cracked the carrier, shredded two spider gears, wore out the carrier center pin, totally obliterated both sides of the clutch packs, steels and fibers, including tearing off all the clutch "TABS", and destroying one carrier bearing and damaging the pinnion bearing. It was a total mess.

P.S : What I have done to my truck and what I am planning to do to my truck is my buisness, so please reframe from making comments or using me or my truck in discussions that they should not be in and when the info being used, is not close to being accurate. Thank-you.

 

dont flatter yourself, your truck was used as a comparison reasons to deside if one should go n/a or supercharged.

 

Don't worry I'm not "flattered" at all. I just wish people would get their FACTS straight before talking about someone else's buisness. Because it makes them look like dunba$$'s. And frankly I'm getting sick of it. People look in my GALLERY and assume THIS and THAT, but in fact their not even close. I guess some of it is jealousy and some is envy. But what ever it is (and I don't really care) they can just keep it off the boards.

 

what facts are you talking about? if your going to call someone a dumba$$ then prove it, or that going to be like the 340 hp and 13 second times (there are some facts for you)

without getting into a whose is bigger contest, i am neither jealous or envious(no need to go any further with that). sirket gives you a lot of praise.

i have absolutely no idea how this thread offends you. if you dont want anyone to talk about your business, then quit posting about it.