Well, I've had a chance to get my car on the dyno, and the results were disappointing to say the least. I feel as though it definitely should have made more power than it did, but to all the engine guys out there, what am I missing here??

SBC 350
Bored 0.030" to bring it 355
Scat rotating assembly, 6" rods with flat top pistons
Edelbrock e street heads (2.02/1.60...64cc)
Comp cams 1.6 roller rockers
Trick flow HYD flat tappet cam (.512/ .528 total lift)
Edelbrock EPS dual plane intake
Holley 650 brawler double pump
Msd billet dist
Msd 6al ignition box
Msd blaster coil
Msd plugs
Msd wires
Flowtech shorty headers
Flowtech y pipe
3" single flowmaster exhaust

The car is 5spd manual, with a 3.90 gear...they did 6 pulls (all in 3rd gear for some reason...).

It made a measly 305 hp, and 313ft lbs to the tire on the final run which was also the highest numbers.

We're my expectations set too high, or are those numbers on par with what the info provided says kt should be making??

I was hoping for at least 350...

 

I am thinking it is being choked from the head ports out. Those flowtech headers are not particularly good nor is their Y-pipe. Flowmaster is about the single worst performance muffler you can run. Also that intake manifold is not doing you any favors. I bet a 1" open center carb spacer and a 3" cutout would net you 20 hp. Probably alsl gain another 10 hp in 4th gear.

 

Thanks for the reply.

I've been wanting to upgrade the exhaust for a while now. I was thinking going to a long tube header and ditching the flowtech shorties. The only issue I can see with doing that is ground clearance as my car is lowered...

 

How much cam duration?

numbers seem decent to me but yeah the exhaust side probably will free some power up

 

284/290 duration, 110 degree seperation.

If these numbers seem okay to most, maybe it's time I think about doing not only the exhaust, but a new more aggressive cam...roller perhaps

 

Well cam has some size but a roller is better for lifespan and more area under the curve since lobe can be more aggressive. But i realy think the heads need work to make great gains. They arent really hot performance heads.

Id try exhaust first tho but probably few hp to be found there. Maybe not substantial

 

Those flowtech headers and Y pipe are absolute garbage. The T connection and 2.5" piping are a joke. Ditch those and the blowmaster exhaust and you will see good gains

 

Those are pretty decent numbers with poor flowing exhaust and marginal heads.

Get some decent exhaust and switch to AFR heads and a proper roller cam. Power will go WAY up.

GD

 

Maybe that dual plane intake is holding you back as well?

 

You can make a lot more power with a 350, even with the heads you have. You have to be very picky about the intake/carb/cam and the exhaust you use. I never had any luck on a good performance small block with a 650/dual plane combo, and although you gave a couple specs on the cam, there is a lot more to it than lift and duration. Small blocks are very sensitive to lobe centerline and cam degree, also flat tappets are robbing you of some horsepower. Decide on your rpm range (you can't get much more than 6000 with those heads), give the tech guys at the cam manufacturer a call and give them the details, all of them. They will likely set you up with a milder version of the cam you really want.... that way you 'll come back in a couple of months and buy another one....

 

Funny thing about it is that I'm on my second camshaft in the past year. First one was an edelbrock 2102, wasn't enough...so now I'm with the trick flow cam and it's still apparently not enough.

 

That cam is enough to make more power if the rest was there to support it imo. Better the head and intake the less cam you need and vice versus

 

More cam won't help poor flowing intake, heads, and exhaust. You have plenty of cam. You need some AFR 195 heads, intake for your intended power band, and quality exhaust like Dyno Don headers/Y-pipe, and 3" to the bumper.

GD

 

Thank you for the input. Exhaust is definitely on the to do list this winter...Heads may be out of the question as the e streets only have one season on them, so i'd have to sell them quick before i'd be able to pick up some new afr heads.The intake is also new, but more attainable than the heads for me.

That being said, what intake manifold would you suggest going to over the edelbrock 2701 thats on there now? (I know thats a bit of a loaded question to ask...lol)

 

Performer rpm imo would be better.

 

Those heads aren't "max power" heads. That's just simply not what they're designed to do. They're not "bad" or anything, just, MANY other heads have the ability to make more power. I wouldn't be in such a hurry to yank em though, until putting the effort into getting out of them whatever they'll give. Which isn't happening now: stock GM heads can do better than what you're getting now.

I agree with Orr, a Perf RPM intake would be MUCH better. That would be my choice.

And, I agree that there's VAST room for improvement with better exhaust. That would show up if we saw the torque curve instead of just some peak #.

I don't know the details of the Trick Flow cam; there might be some room for improvement there as well. I doubt that you need a "more aggressive" one though; just, perhaps one better matched to what those particular heads want. Of course one with roller tappets would always be better, rollers offer several significant advantages, but people have been making plenty of power with flat-tappet ones since the beginning of time, so it's not "essential" in that sense.

I'd also suggest checking out the usual suspects that get overlooked such as a "drop base" air cleaner for example, which often puts the air cleaner lid within an inch of the top of the carb, thereby choking it before the air can even get into the engine.

You say it has a 3.90 rear gear. Sounds like a Frod 9". If so, that consumes a fair amount of power all on its own. Probably 25 - 30 HP more than a 10-bolt would. That needs to be taken into account in figuring out why the # seems lower than it should.

You also don't mention any tuning efforts being made on the dyno, nor provide the torque or HP vs RPM curve, nor even mention what RPM it peaked at, nor provide a A/F ratio chart. Just sticking a car on a dyno and looking for a big # and complaining that whatever you got isn't big enough is kind of ineffective use of the dyno... a dyno is a tool that allows you to examine in detail the results of changes in real time, not just a thing for printing out large pleasing numbers.

 

Thanks for the input.

The intake is on the list of upgrades, along with a full exhaust overhaul. I'm not running a drop base air cleaner as I've got a cowl his so I've got the room for a normal one.

The rear is a 4th gen ls1 rear with the 3.90 gear, not a ford 9"...not that it matters as the gear will be the factor in power loss.

Unfortunately there was no tuning done while on the dyno. It was a local shop putting on a "dyno day"...so you make your three pulls within a 15 minute window. They ended up doing the first two runs up to 4600, the third run the car was heat soaked bad. So because they screwed up they did three more after the car cooled down...

The guy doing the pulls also seemed like he wasn't sure of what he was doing, making all runs in 3rd gear instead of 4th (5spd car), so there's a little loss there aswell...

 

Well, the LS1 rear is a 10-bolt, so that excuse can't apply.

They do the pulls in a lower gear because the dyno has a speed limit. (no, it's not like a cop is going to bust it...) The rollers can only withstand just so much RPM. Even with a 3.90 gear, the rear wheels would be doing around 118 - 119 mph at 6000 engine RPM. I don't know what the limit is on the particular dyno you were using but that's ALOT. Most of the time they'll want to keep the dyno below 100 or so, which 3rd gear would put it at around 90ish mph at 6000 RPM. Much safer. The loss isn't particularly great, not enough to use as an excuse.

The way a typical chassis dyno works is, the operator sets it to allow some specific acceleration rate. I don't know if you noticed, but no matter how much power the car that was on it had, it sped up at the same rate... that's how it's designed. That's a setting the operator can change. For a typical street car, the rate will be around 200 - 250 RPM increase per second of the run... meaning, to get from say 3000 to 6000, will take around 15 seconds. For a pure drag car, let's say a ProStock or Modified or something, a more appropriate rate might be closer to 500 or even 600 RPM/sec. The dyno loads the rollers with the appropriate load to regulate the acceleration to the rate it is set to, which ideally, corresponds to the engine's expected rate in actual use. Its measurement is related to how much load it has to put on the rollers at any given moment to maintain that constant acceleration rate. That's why that kind of measurement is affected by drive shaft mass, wheel mass, etc.; all of those things are accelerating too. This is as opposed to a typical steady-speed dyno, such as a Mustang or an electrical one, where the roller system acts as a generator and the electrical output is measured. Those allow setting the engine to a constant speed and measuring its output. Each method of measurement has advantages and disadvantages, but knowing how it works is central to understanding the numbers it spits out.

Also, there are "corrections" that the operator can apply to the raw measurements. For example, s/he can input the altitude density, which "corrects" for the concentration of the air, according to pressure, water content, etc. Most of the time, operators put in REAL GENEROUS "corrections", because that inflates the numbers and makes paying customers not feel like their p**** is small. Southern California is notorious for that, for example... I would NEVER trust a raw number out of ANY of them. Not that they "lie" or anything like that; just, the numbers they come up with aren't likely to be duplicated anywhere else, or corroborated by other measures, such as track mph. If your operator didn't do that, your numbers might be VERY conservative, maybe even BELOW the "actual" engine output.

However all that may be, the absolute number a dyno spits out isn't NEARLY as important as the results of changes, while the settings of the dyno and the ambient conditions remain the same. IOW, make a run; increase fuel by 3%; make another run, see what happened; if it got better, increase the fuel another 2%; and so on. Again, the ABSOLUTE NUMBER the dyno spits out, whether you're looking at torque OR RPM, isn't near as important, as the results of the changes.

Your typical speed shop "dyno day" is not designed to provide this kind of information, and as such, is FAR FROM the most efficient use of dyno $$$. Other than the pleasure of hearing your car wind up into a load, you basically got almost nothing for your money.

Fix the known problems with your combo and see what the results are. I'd suggest going to the strip and getting a baseline, and after any changes, going back to get new numbers. Keep in mind that with a stick-shift car, THE DRIVER is absolutely CRITICAL to the process: any inconsistency, in things like launch RPM or shift points, will affect the mph (ET is irrelevant for the situation at hand) and confound your attempt to measure the effectiveness of your modifications.

 

Unless it's some really old dyno..... most of the entry level Mustang Dyno's are good to at least 150+ MPH. The entry level Mustang is 165 MPH in 2WD mode. My Dynojet 424XLC2 is rated to 200 MPH. Usually we select the gear that will be closest to 1:1 engine-to-driveline ratio. On a 5 speed manual transmission car we usually do WOT pulls for tuning in 3rd, and for record in 4th. And yeah we hit speeds in excess of 150 MPH all the time. You can't help it when doing pulls in a Hellcat Redeye with over 800 at the wheels. The drum speed gets up there in a hurry!

What you describe is one of the modes of a "loading dyno" - now if you are talking about a Mustang (which I am less familiar with as I don't own one - but I do work with many tuners that have owned/used them extensively) - these are by definition loading dyno's as they use eddy current brakes attached to multiple small diameter rollers to restrict the acceleration as you describe, but this is not how all dyno's work - specifically in the case of Dynojet (when being used without the load absorbers engaged) - you have an inertia dyno rather than one based on eddy brakes. The drums on the Dynojet are 24" in diameter and weigh about 2,250 lbs each. The Dynojet works by measuring the acceleration of the drum, and by calculation/lookup tables, determines HP directly. Indeed it requires no operator input at all - you simply load the car and make a pull. You only need RPM signal (or RPM calculation based on gear ratio and drum speed) if you also want a torque curve (not required as you can graph HP vs. MPH). There is ZERO operator input for vehicle characteristics. Just customer name and make/model/year for file organization. Now - if I want to turn on the load absorbers, I can do as you describe or I can absorb as much as 1600 HP and simply stop the car from being able to accelerate past a given MPH or RPM.

Depends on the dyno. Mustang's are subject to operator "correction factors". Dynojet's are not. There are no correction factors other than ambient temperature and atmospheric pressure - which it has a probe for. Yeah you can take a heat gun to the temp sensor...... but we generally don't do that.

Absolutely correct. It's about comparing to previous runs on the same dyno. It's about refining the tune - changing timing and fueling to get the best number, etc.

Dyno days are a pissing contest. Period. No tuning is done. It's just about making more power than your friends. The numbers are only comparable on the same dyno, on the same day.

GD

 

I agree with everything that's been said in here.

I know the car has some required work/upgrades/tuning that needs to be done. The purpose of this thread was not to start an argument on dyno vs dyno...rather to see if the information provided about the car coincides with the dyno results. I was expecting different from the car, the engine builder (who has been in the business building race engines for over 30 years) who was also there during the runs was also very confused and shocked at the low numbers. He did an identical build for a corvette with the exception of the headers and exhaust system, and the car made 420hp to the tires.

I know that its apples to oranges to an extent, but almost 120hp difference from an identical engine is a bit of a stretch in my mind. Maybe my way of thinking is wrong, I dont know...
I appreciate all the input thus far, and if anyone has anything else to add, by all means speak up!

 

I DO NOT see 420 wheel worth of engine in that build list. That would be about 485 crank HP from a flat tappet 355........ NOPE. Your builder is blowing smoke up your skirt.

Here's Blueprint's 355 crate offerings and their ratings. The highest engine dyno rating is 385 CRANK HP on a flat tappet:

https://blueprintengines.com/collect...cement_355-c-i

So where's the extra 100 crank HP coming from on your build? It's not in that parts list I can tell you that.....

I can see you making 385 crank HP and with 15% drivetrain loss you are looking at 327 wheel. Which I can see possibly happening with some tuning. 420 just isn't there friend.

I have seen a number of NA 350's on the dyno. And my tuner's have seen about 40 years worth of the things between them. They come and go all the time on the dyno. They ALWAYS make mid 300's. It's very rare to see anything with an NA 350 on pump gas eclipse 400 wheel. We just don't see that.

GD