308 carb airbox restriction discovered

Well everyone, weren't some of those last posts special?

For those of you who have just tuned in:

So far in this thread, we have seen that there can be recaptured rwhp (10 - 12+) from removing the very flow restrictive sound deadening mesh and packing in late 308 GTB airboxes. This hp gain is added to further perhaps on the top end by using shorter velocity stacks.

The sound deadening mesh with it's fiberglass packing is easy to remove, and several FChatters have already done so. Spasso, a well known Tech Section overachiever, even brilliantly built a beautiful air snout extension (documented early in a thread later hijacked: http://ferrarichat.com/forum/showthread.php?t=50136 ) to further promote cool airflow. His initial driving impressions did indicate a possible secondary lean situation with the stock jetting that he is addressing. He described 'running out of umph up high, which would be consistant as that is where the flow improvement would be most notable.

With the removal of the sound deadening material, the Weber induction sound is much more pronounced, over the stock box, but not as loud or raw as the individual carb filters.

Webers are well known sensitive to the amount of air above the air horns. Shorter velocity stacks act to increase this area allowing greater high end air flow, possibly at the subjective cost of a little lower end umph. Dynos were posted suggesting around a 5 - 6 rwhp improvement.

With the increased airflow comes the possibility that the carburators will need to be richened, probably by going to 135 - 140 main jets at a minimum. The proceedure to do this is documented here:
http://ferrarichat.com/forum/showth...g+weber+jetting
I personally would add a richer (smaller, e.g. 190) air correction jet for the top end where the flow difference will be most pronounced.

Among the several side discussions, the positive effects of cool air ram vs the popular individual carb filters has been discussed, as well as the possible plenum effect of the airbox and the fluid dynamics of aggregate vacuum producing a smoother flow across a filter element. And, Henry also identified that after the mod there would be more available filter element area available to pick up the dirt. Other side discussions covered just what the hell did these early emissions-control engines put out anyway and how the stock ratings did not neccesarily have some details attached like accesories or airboxes, and that they could have been quoting different engineering standards (i.e. SAE vs. DIN). Things Ferrari seemed to do to pull down the power included not only the subject airbox muffling, but crappy exhaust manifold matching, different cam timings, thermal reactors and perhaps even welching on the stated compression ratios,. I came up with lame brain idea of using porcelin coating as on headers to further insulate the airbox from heat.

Important to note that one FChatter removed the insulation and then found the intake noise too loud for his tastes, and will be reverting to a muffled box.

Later, the proper re-jetting of the carburretors to take advantage of the increased air flow. Corraborating a previous experiences, Spasso now found almost 10 hp over a previous year's dyno from now using the airbox and short stack mod, and increasing his Weber main jets to 140 to cover fuel availability for increased flow. This gave an air fuel (A/F) ratio in the 12s, while best power is in the low 13s. He is now looking at going to a 135 main and a richer air correction jet (200 to 190) to approximate an A/F in the low 13s and ensure fuel availability in the high rpm band. The power gain and reasons why were disputed, and then defended so everyone could evaluate the mods and data for themselves to decide. Duh.

An additional 'lucky sock' modification was also alluded to, but didn't convince a sole. I crack myself up.

It's been a bit longer road than anticipated, but hope some folks have gotten something out of this so far. Spasso and I are also going to write this up for Forza, where it will probably be edited to 2 paragraphs.

best to all
rt

 

Ironically I happen to have one more lucky sock in addition to the one I am using. It quite possibly could be good for another 10 HP if used correctly, possibly doubling the horse power to 20 if used in conjuction with the original lucky sock.


[size=+2]RED[/size] of course.

Further testing will be required..........................

Film at eleven.
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Spasso, Russ, et al,
Rock on! Awesome thread. Great technical information, should help many carb 308 owners out there.

Dave

 

Spasso,

Here is what I am talking about:

The original Dyno that you posted showed a 4.4 hp increase with a stock air box and the miracle short stacks (Not the 5 to 6 hp that was quoted in a recent post, but I guess it is OK to increase the hp# at each new post) For the record this particular car has a history of different baselines (and yes I have e-mails from the owner going back over the past 3 years regarding his problems and the Dyno results) so that a single baseline test on this car before switching over to the test stacks is not as you would want people to believe. I have no doubt that you could run multiple baseline dyno’s for this car and get dramatic swings in hp readings. That car has had to many “issues” to be a test bed for this tread.

Your personal dyno with your multiple mods including the short stacks and gutted air box showed only additional gain a 4.6 hp over just the short stack test you posted earlier.

So which was it?? the gutted airbox, the snorkel, the spark plugs the re-jetting of your carbs .... that gave you the 4.6 hp increase over the. The proper jetting could alone give a significant increase in HP (and Russ knows that). I actually would believe that the majority of your total 9 HP Gain had to do with the air box and the jetting. Why don’t you run your dyno with the stock stacks? One of us will be wrong and yet we will then have some facts and not your assumptions.

The problem with your posts is that you have done so many changes without dyno's between each change that you truly have no clue what made what HP and yet you a make a statement that the HP gain is equally split between the stacks and the air box changes. There is no doubt that YOUR car has had an increase in HP but you can only make assumptions of how that increase came to be and that is where the problem lies.

The whole issue is based on one car with a very checker past (and you know that to be true) and to many assumptions and guesses. As I said before do it right and post the results. You are welcome to turn my questioning of your results into a Kermit issue but that is only a way for you to try and distract from the assumptions that I have brought to light. This is an issue about the tread not any one person so please find another way to try and discredit me. (I will get back to Kermit when “Tim the stick” reports on the destroyed heads).

I am truly sorry to see that Russ has taken issue with my questioning here of the process and the distortions but hey such is life.

Try getting past the questioning and the questioner and deal with the issue at hand.


Paul

Gee I hope this is not considered a Hijack by our moderators.

 

You didn't buy that sock from Kermit, now did you???

BTW, shouldn't it be yellow?...

 

Paul,
You are correct. I did not dyno between each modification as would be warranted in a true control experiment and no, it is not possible to determine which modification made what percentage of the horse power to the "Nth" degree.

YOUR presumption that the short V-stacks do nothing to increase horse power is also at fault. The proximity of the stock stacks to the top of the airbox limits overall flow. This is the reason the short stacks were designed in the first place.

I honestly don't believe that simply gutting my airbox and going up a size in main jets got me a full 9 HP net increase. This is based on the experience of others. It also leads me to believe that the short stacks did indeed have something to do with the increase. That is my OPINION. My opinion is based on past experience with another car I have with three Weber DCOE side draft carbs. .

So, upon seeing the dyno on Stewarts car with a 4.4 HP increase with short stacks in a STOCK box says what? 9 net HP increase on my car minus the 4.4 gain on Stewarts = 4.6 (like you said). No, this isn't a scientific conclusion but it points to being a logical one with an error factor determined by the type, year, engine condition etc....This you don't agree with, so be it. I will leave it to others to make their own conclusions. All I am doing is sharing my experience with this project and my OPINION.

So I'll make this easy for you to understand,
IT IS MY OPINION that the short stacks CONTRIBUTE to the net horse power gain when gutting the airbox and going up a size in main jets.

As far as Stewarts car having an inconsistant baseline, baloney. Unless an engine is going through the throws of self destruction, the ignition system is self destructing (which it isn't, Electromotive), or the fuel system is malfunctioning (which would be obvious to the dyno operator) it should post fairly consistant numbers within 5% over and over and over, changes occuring as the engine and vital fluids get hotter and hotter. Unless somebody starts turning screws and changing timing it will do it over and over and over.

 

The socks are my own special buy to go with my lucky (red) shorts.

 

"I know the owner, and he has never described such an anomally. He has only stated (and supported by the dyno runs I witnessed) that it did not make the hp that Nick and Kermit had initially claimed he should expect from their performance rebuild of his engine." by davehana

It did not even make the HP of a stock 308 Mr. Hana! after it was was rebuilt by one of your other friends.
Here is an excerpt from an e-mail sent to me by the owner of that car (where you there?):

"If you guys had looked at Zonker as a marketing opportunity it did not work well at the dyno coming in 10 HP LESS than John Miles' stock 308. Many of the local Ferrari guys were there to witness the "oops"."


The "performance Rebuild" on a carbed 308 and only 188 rwhp and before that run it was 10 hp less then a stock 308 I think you just answered your own question. What happen to the performance part of the rebuild?? I don't believe Nick rebuilt that engine but only sold the parts which by the way I have also bought an am very satisfied with.

10 hp less than a stock 308! Think I have proved my point.....

I have many more e-mails from the owner if you need them.


I do not want to be accused of hijacking so I have now answered your ? please now get back to my questioning of all the assumptions and misleading data regarding Dyno runs and HP gains for mutiple changes on an engine. It was legitimately posted.

Good Night. I can't wait for a real answer in the morning.

Paul

Spasso,


"The proximity of the stock stacks to the top of the airbox limits overall flow. This is the reason the short stacks were designed in the first place."

I would suspect this is another one of your opinions as I don' believe you have any data to back up your knowledge of flow or what the engineers who designed the setup were tuning it for?

I appreciate that we are now learning that these were all asumptions and opinions.

Paul

 

I think we are rapidly approaching the TMI zone.

Thanks again for the ignition info - if you ever stick a timing light on the flywheel though, let me know what your static timing is set at.

 

Paul, you proved your point? I'm sorry, you missed the point of my question. Your original statement was that the car was incapable of establishing a hp baseline, because of "dramatic swings in hp". Here is your quote:

"I have no doubt that you could run multiple baseline dyno’s for this car and get dramatic swings in hp readings. That car has had to many “issues” to be a test bed for this tread." quote from Paul Sloan.


I questioned you on this statement, and you avoided the question, and ranted on about how low the hp was on the rebuild of this engine by Kermit and Nick. That is not part of this discussion. The discusion is on the short stacks, and your claim that the dyno sheets provided are invalid, because the car used has "dramatic swings in hp".

So, back to my question: What is the evidence you have that says this engine has "dramatic swings in hp", that would make it suspect for use in establishing a baseline, for these short stacks?

As you mentioned, yes, I was present with many members of our local FCA chapter when this car was on the dyno (and btw, John Miles car was hardly stock ), and again, I did not see any "dramatic swings in hp" from this engine (they were CONSISTENTLY low). The fact that they were low is irrelevant to the discussion...it is the consistency which is of issue, because you are claiming the dyno charts shown are not relevant, due to the "dramatic swings in hp" the car is supposedly capable of. I am simply asking you to prove this point.

Dave Handa (not Hana...)

 

No problem questioning the process at all. It's always cool to hold folks objectively accountable for their positions.

Let's keep the passion to being about Ferrari, not the defense of our positions at all cost.

In perspective, all this thread is talking about is a 10 horsepower and $100 mod in a hobby. Nothing more. There is enough info already ON TOPIC for everyone to be their own judge.

Summary: Spasso thinks that his hp gain is due in parts to the airbox mods and short stacks. Paul Sloan thinks there is not enough information to really say that definitively. Both legitimate positions. End of neccesary value added to this thread.

Let's all move along, nothing else here to see.
Looking forward any new suggestions or ideas.
best to ALL
rt

 

I'd be happy try a set of short stacks and volunteer my car as more beta come the next fchat dyno day here in So Cal. If there's not too many cars in line, I could dyno /w/ the stock stacks and then the short stacks. Swapping the stacks wouldn't take long at all. It'd be another data point to add, and i am curious as all git out. This is still an utterly fascinating thread!

 

Guess I'm going to throw in my $0.02

Paul,

Everyone knows how you feel about Kermit. You already have another thread here on it. Can't you just keep it there...what's next a whole website dedicated to bashing Kermit?

I'm well aware of you on this site, as well as Dave, Russ, & DJ. I've never met any of you personally, but would consider Dave, Russ, & DJ friends just base on their demeanor and courtesy on this site. It is fine to disagree with someones "opinions" but why attack them? I'm sure not everyone agrees with my opinions and not everyone likes me (why, I have no idea). Why don't we do like Rodney asked..."Can't we all just get along?"

Too much excitement, I'm going to bed.

Henry

 

hankum,

I think I made my point clear that this was not a Kermit Issue and you bringing it back up is truly sad. As I said earlier when Tim the Stick see the heads and issues his report you can rehash your Kermit defense issues. It is unfortunate that some cannot distinguish between my well placed despise for someone and my questioning of data that I believed was inaccurate and misleading.

My questioning of the data based was legitimate and well substantiated, the reply by Spasso at the end I think proved my point which clearly stated that his interpretation of the Dyno results were his opinion and that too many changes were made between Dyno runs to give scienitific (factual) credit to any one device.

The concept of the thread is good and I do believe that Russ and Spasso have proven certain things but when you start promoting a product with opinions that are being portrayed as facts this is where it goes wrong. NO MATTER WHO MAKES THE PRODUCT!

As for my attacks on Spasso or Russ I don't think that has happened, if no one is allowed to question a post (as long as the questions are legitimate) then what good is the exchange. I never attacked Russ or Spasso but I did question them (more spasso).

As I said before Russ has given me great help in my project and I believe that even after this exchange he will continue.

I actually think and hope that if I asked Spasso for help I would receive it.

There are those that troll and question to annoy but I do not think my questions were baiting in any way. When asked for proof by Dave about the test car in the first Dyno I gave him proof directly from the owner yet that did not satisfy him ( and knowing Dave's position nothing will). It satisfied me and I have no intention of embarrassing the owner of the car in the public forum by posting anymore of his e-mails. IMO that car is sick and the "performance rebuild" (still trying to figure out where performance comes in to play with a 188 rwhp) was done by the same guy who developed the "short stacks" so please where is the independence? We are talking about a 2.1% gain in rwhp (1.8% at the crank) in a car that has had different dyno baselines each time it gets on the dyno. When you are dealing with such TINY increases in HP the test mule must show some consistency over a several runs to show a true average.

I have asked my questions and had my exchange and I am satisfied with the response of both Spasso and Russ. To the others who wish and discredit me with claims of attacks and other issues so be it.

I have been working on Ferrari engine project for a very long time (it was delayed a year) and I have used the PM function to get advice so that I can avoid those that attack without merit or question just to annoy. Ferrari Chat has some very good people and it has some very stupid people on it. I learn every day who is who. In one case I learned way to late!

With regards to your 2 cents I think you are a penny short to say the least so maybe you should be the first to install the $100 Oldsmobile connecting rods in your Ferrari, I will look forward to your 1st 8500 rpm Dyno run results(confused? do a search).

As always it has been a pleasure but it is Time to move on.

Paul

 

.........................and so you've managed to turn yet another post into a rant about how Stewart's car has been ruined by Kermit and/or Nick, you have offered NO CONSTRUCTIVE perspectives to the discussion, only detractions from every statement made and ABSOLUTELY NO SCIENTIFIC PROOF to back up your claims that the stacks DON'T work. It is mere conjecture on your part.

You have proven numerous times that you will only address the questions and statements that suit your crusade and ignore the ones that may solidify the possibility that the short stacks may indeed contribute to the HP gain. People on this site aren't as stupid as you think. They can come to there own LOGICAL conclusions just as I have. Opening up induction on a car is not rocket science.

You are transparent in your intentions.

I am in the firm belief that if these stacks were made by somebody else you wouldn't have cared one way or another. It's obvious to everyone but you.

I honestly don't believe I can help you or offer any advice based on the 35 years of experience I have working on cars. You will hear what you want to hear and ignore the rest. That is obvious in this thread also.

So I'll make this easy for you to understand,
IT IS MY OPINION that the short stacks CONTRIBUTE to the net horse power gain when gutting the airbox and going up a size in main jets.

They do work, maybe only for 1 HP BUT THEY DO WORK. [size=+2]You cannot argue with physics[/size]

YOU ignored this next statement so I will post it again;

As far as Stewarts car having an inconsistant baseline, baloney. Unless an engine is going through the throws of self destruction, the ignition system is self destructing (which it isn't, Electromotive), or the fuel system is malfunctioning (which would be obvious to the dyno operator) it should post fairly consistant numbers within 5% over and over and over, changes occuring as the engine and vital fluids get hotter and hotter. Unless somebody starts turning screws and changing timing it will do it over and over and over CONSISTANTLY.


Sorry about your heads. Nobody deserves this misfortune.

In the future I will hesitate to share any of my modifications or experience in public for fear that the thread will be hijacked by a "muck raker". As far as I am concerned you have cheapened the experience for everyone regardless of the so called "public service " you think you are performing.

Too bad

 

Please do not take that route. The threads concerning modifications to the older cars are perhaps the most interesting element on Fchat these days. Post your thoughts, and if you feel a thread is going the wrong way, please let Wayne & Omar and the other tech mods know.

 

Second this.

FWIW, I think you and Paul are now fighting over an issue not worth fighting about. You've both posted your opinions (thanks). Now let's move on.

Is anyone going to make a dual snorkel box?
Philip

 

Philip,
THAT would be interesting...but what about venting to oil cooler? How would that be accomodated?

 

If someone wants to send me a snorkel off of a 308 airbox, I'll install and weld it on the airbox contralateral side to the stock and pipe it to the left sided scoop. Will place a nice elbow off of the fiberglass scoop piece to accomodate. Gotta have it look stock so I don't loose those points at Pebble....
The Mondial oil cooler already has a fan, so less of a problem.
I do think it would make a difference.
best
rt

 

I think you could get away with a splitter in the driver's side snorkel, rather like the later cars had on the passenger side possibly with a fan on the cooler too. You'd want the snorkel to be able to clear the oil filter.

The Michelotto car(s) had something along the same lines.

 

Slightly off topic here, but I think Philip is right on the mark with the suggestion of a fan on the oil cooler even without splitting off the L/H inlet for a dual inlet airbox. Sitting in traffic on a hot day the cooling system would benefiit greatly from additional forced air running through cooler.

Mmmmmmmmmmmmmmmmmmm
I feel another project coming on.....................................

 

I love this thread on the modds that you guy's get upto over in America. I will be getting some of the short stack for my gt4. I will hopefully post my unbiased results for everybody to question I think Spasso and the other tech guy's do a good job on giving their experiences. Putting a car on a Dyno is both costly and time consuming. I have seen a double intake airbox on a 308 gtb Michelotto car. It looked like that the additional feed was the original one turned upside down and welded on, giving a greater ram air effect once on the move.

 

There is the possibility you will have to modify two of the low profile stacks to fit inside the footprint of the stock air filter element. A bandsaw and belt sander does the trick or you can clamp up the stack and use a sabersaw and dual action sander clamped in a vice upside down.
See this thread for pictures.

 

Dual snorkle on Dino 4 valve: Photo's courtsey of my cousins collection which includes 5 Dino 4 valve engines out of I believe 12 made and 4 Lancia championship statos's. No other comments.
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