400 hp 302 with stock internals

[dragogt]

http://www.airflowresearch.com/articles/article087/A-P1.htm

Big heads say what...

 

[5.0Flareside]

not that big of a surprise...

 

[dragogt]

I realize that..

 

[DNFXDLI]

Small ports and runners though...that was my 4 bbl point...those heads have huge ports and runners.

 

[dragogt]

http://sbftech.com/index.php/topic,27216.795.html

Engine Torque Down Low and Heads Sizing SUMMARY

Folks....... before reading, a few things need to happen so you can understand this summary. First and foremost..... please reread the OP of this thread. Here use the following link = http://sbftech.com/index.php/topic,27713.0.html to really understand what this topic is about, or in better terms, what is NOT about:

NOT a maximize cylinder heads for TDL or HP or driveability topic, but a combination of all.
NOT a port old iron heads topic.
NOT a gain knowledge with a grinder topic.
NOT a street racing or ricers killings or a SOTP HP happy dyno topic.
NOT a class racing setups exclusive topic.
NOT an Engine Masters Dyno Competition setup
NOT a 100% OEM/stock style setups exclusive topic.

That explained:

1. For ages, anything in the 185cc, 200cc, 210cc, 240cc intake volume range has been taken, viewed, experienced as TDL killers when a 289 or 302 engine setup was involved. Those big head - small engine (BH-SE) setups were thought as requiring higher camshaft durations and lift to maximize their use for EVERYTHING ..... in error. The reasoning for the error with those setups back then was the misconception summarized as..... bigger port = slower A/F stream hence, hello "V" or velocity.

2. Intake port volume figures or values mean ****, period. It's the Cross Section Areas (CSA) you need to focus on. Maximum, Average, Minimum and their location within the port.... or better known as geometry from port entrance to valve exit. To refresh your memory on the topic, do suggest to check the info at http://sbftech.com/index.php/topic,2226.0.html. It also shows why a TW 170cc, a stock style 185cc inline valves head and a 195cc Hi-Port design are said to have similar ACSA's. You might also want to check a very good explanation saying the same thing we have discussed so far, regarding the BH fallacies, at http://sbftech.com/index.php/topic,27944.0.html thanks to matt0matic's find elsewhere, on the same topic, focused on the LS6 vs LS3 heads.

3. There are other items that also affect "V" yet were always ignored, taken for granted or simply not understood, let alone not experimented with in the past. A small intake volume windsor head can be configured to generate impressive performance results, that has never been in doubt and has been proven by many class racing champions, record holders, etc. However, the REAL cost to achieve such results, are far more expensive than selecting a "previously perceived as too big" sized set of aftermarket heads..... which BTW.... is part of the requirement for this thread. Old iron heads are not an option, the tinkerer/enthusiast have decided to go with an aftermarket alternative...... what does he/she need to know/understand and look for; previous to making a decision? DO YOU now understand why porting iron heads was NOT relevant to this topic?

4. A specific setup aimed at complying with some requirements that does not need much camshaft duration, is NOT a compromise..... or is there a specific, ideal, target intake duration value to settle for? .... Just like the .998 vdc TPS mythological "tuning value"? . Less duration to do the intended application job = a more efficient head design..... NOT the other way around.

5. Does the above mean that any 302 with TW 190 FAC heads (as an example), 210cc inline valves heads or 215cc HP heads, that is not using a 238° intake duration cam @.050" is a compromise?..... NO, everything does and will depend on the application, application, application.

6. A BH-SE street/strip setup can be designed using a small intake duration/high lift camshaft profile ....... this does enhance setup driveability, TDL is ensured for street use, overall fuel efficiency is usually a side-effect, WITHOUT having to worry, or cause excessive valve train wear and tear by simply setting it correctly. Will it cost a fortune when compared to the alternate? + .... This is a fact, not a tergiversated speculation based on inexperience.

The term 'compromise' has been used extensively throughout the discussion in this thread however, with the wrongest of its connotations... . A compromise is a settlement above the retention of a specific goal. IOW.... if you sacrifice driveability or emissions from a setup to reach your performance goal...... you have made a compromise as well. This is typical from the conventional high duration/mid-lift setups.... isn't it?

On the other hand..... if you do not sacrifice driveability, and still reach or surpass your performance goals..... no compromise whatsoever has taken place. Which is EXACTLY what the OEM's have been doing for the past decade and a half or so. They are NOT compromising performance, nor are they doing so regarding all the other emissions, CAFE, etc requirements they have to comply with....... they are designing to fulfill ALL of them. Summarized..... NO, they are not 'UNDER-utilizing the cylinder head' as wrongfully perceived. The fact of not understanding ALL the requirements they have to comply with, does not mean they are 'UNDER-utilizing the cylinder head' when a tunnel vision approach or view is used based on a single item or characteristic only.

Nevertheless......and this has been a very positive outcome from their new "cylinder heads sizing" approach, if you feel like a compromise in emissions, driveability, fuel consumption is not a problem for you....... you can then work within their stock cylinder head designs (better than an OEM old iron) more effectively to further the output focused on performance only, and compromising all the rest. Get it?

Or when have you seen OHV and OHC stock cylinder heads, used in everything from trucks, sedans, luxury cars and sports car...... capable of 300+ CFM flow figures, in the 195cc for the 5.0L and 260cc for GM intake volume ranges? Or a little, stock 5.0L DOHC engine, untouched internally, be able to run 10.9's N/A, rev to 7500 RPM, with small 260°/263° Advertised Duration, 0.472"/0.432" valve lift camshafts events, using 2.1 ratio rocker followers, although independently variable and valve springs specifications of 60# @1.575" closed and 146# @1.103" open? .... And yes.... OHC setup springs have less mass to control when compared to OHV setups + there's the benefit of the Ti-VCT system ±25°/cam timing flexibility, yet a proportional comparison using it as a baseline, is more than feasible and valid to use.

BTW..... doesn't the Coyote prove wrong (at a certain degree) the small duration-high lift generalization? The system is PCM controlled for timing events individually yet the total duration-lift area per valves remains fixed..... doesn't it? IOW..... when you depict the Ti-VCT system, it looks something like:

Neither side waits for the other, though..... they work 100% independent from the other.

 

[dragogt]

Continued..

Think about it..... a 260°/263° Advertised Duration, 0.2348"/0.2160" LOBES lift profile, with ~195cc stock heads, capable of a stock 7000 RPM redline (higher when tuned)..... and an open valve spring pressure typical of a closed valve OHV HR setup spec? ..... yup, technology has been busy evolving. It is funny and entertaining every time I read the "compromise" excuse or explanation regarding the OEM's based on ignorance...... AGAIN, an OEM BH-SE setup, capable of running 10's, w/out touching the "compromised" STOCK ENGINE?

NOTE:
This is NOT a Coyote engine topic either, it is simply used as the "stock setup baseline tool" to demonstrate how technology has evolved from the 221/260/289/302 windsor years and the performance we could only dream about using, again, a STOCK ENGINE.

Bottom line is .........


If you are looking for aftermarket heads for your 289/302/306 or 331/347/363 stoker street/strip candy...... DO NOT fall for the outdated/obsolete, smallish "V" excused head alternatives.

A. You can ensure driveability and performance 100% better than with smallish 165-170cc inline valves heads.

B. Shoot for better (usually deemed as "too big") flowing heads and use the valve events to control/manipulate "V" requirements for your application. For the 302/306 the "too big" heads has usually started in the 185-195cc inline valve heads area, and the 205cc range for any stroked 8.2 deck setup that will also see street duty. Whereas in reality (and you can check the examples shared here), 302/306 setups will work great with 210cc inline valves heads and proportionally bigger for the strokers crowd.

C. Do NOT over-think the valve train, simply set it correctly and as required by the camshaft specifications. Anything you choose to add in order to make your setup more robust, it will simply add to the same safety factor a traditional or conventional will also have. And NO, BH-SE setups do NOT require valve train setups with costs in the thousands of $$$, like a slogan goes..... just do it.... and you'll find out.

D. The caveat here, if there is one, is simply that there will come a point when the cylinder head can become too large. Typically speaking, that point would be where the duration of the cam gets so small to make up for the "too" large ACSA of the head that "torque down low" and acceleration begins to suffer. But that point is well above any "average guy" off the shelf "Windsor" heads that are available to date. Now.... how does this all relate when forced induction is introduced?

E. More efficient cylinder filling over a more broad rpm range is available with the BH-SE cam approach. High rpm power without killing low rpm manners, which is ideal for the street/strip crowd. Down the road if a further "compromise" in driveability is not a problem, with a simple cam change, you can utilize the induction package to make an all out screamer with no concern for the low end if you so wish. Only a cam change........ as opposed to a new induction package, a larger percent of your money spent once as opposed to twice for a more efficient induction package that is at home on a wider range of displacements, applications, etc. IOW.... you do NOT "compromise" versatility.

F. Same goes for competition setups. I think this portion can only be proven with a video clip of a little 306 Mexican engine, 100% N/A, automatic transmission, shifting at 8700 RPM and crossing the traps at 9200 RPM from one of the contributors to this site, Rich (fast88). The heads used?...... TEA TFS TW 205 or the equivalent to a set of 216cc inline valves heads when their ACSA is used and compared to keep it "apples to apples".



Yup.... engine performance using those "too big" set of heads on that 306 was "compromised"....... .... it might have performed better with a set of 165cc or 185cc heads.

IOW..... for a street/strip setup that will see some or a lot of road, settling for the high "V" crap, small ACSA IS a compromise on both arenas...... streetable manners AND performance at the track every now and then, or always.

And here's the answer I use every time I get the "those heads will be too big" observation/comment at the shop....... "don't worry, I'll correct it with the brain (aka camshaft)." Besides..... isn't that exactly the main job of the camshaft?

Short-Short Summary is:

1. Compromise on the cylinder heads and you will have to compromise on everything else regarding your setup. Do NOT compromise on the heads, and you can choose better and more efficient setup configurations based on your goals/needs.

2. It's less expensive and budget safekeeping oriented to do things right the first time over repeating to correct for drawbacks and falling short from achieving all the goals you set ..... always!

3. Do NOT fall for the "line item cost" fallacy, it is always the "Bottom Line" at the "TOTAL:" row what really determines the budget. Reason why working on old iron heads over the aftermarket available out there........... is a no-brainer cost, performance and budget wise NOT to do.

4. Ensure A/F flow via the cylinder heads and control "V" via the camshaft events and peripherals ...... or is that simple guideline too difficult to understand?

Hope you enjoyed this little novel......

 

[DNFXDLI]

I agree but we are now talking aftermarket heads with different designs than the old 70's 4bbl heads which is what I assumed we were talking about. Looking at the 3V CHI ones I have, yes the valves are large but the runners/ports are small.

 

[dragogt]

My point being that heads normally "assumed" too big for a street engine, can actually work out quite well...

Same thing with carburetors.... (pick the standard and then go 1 or 2 sizes up)

 

[F 150Cobra]

im getting 165CC AFR's this year

 

[5.0Flareside]

im getting 165CC AFR's this year

YES WINNER WINNER!!!!!!!!!!!!!!!!!!

 

[1970Custom]

My point being that heads normally "assumed" too big for a street engine, can actually work out quite well...

Same thing with carburetors.... (pick the standard and then go 1 or 2 sizes up)

That's a relative term; too big of a carb will usually warrant a dog down low but perform great at higher RPMs, Too big of a turbo, gobs of turbo lag but once spooled can produce large amounts of boost, etc...

 

[dragogt]

Damned if I can find it now, but I remember an article where they took a 1000cfm carb changed the boosters and venturis (??) and made it run quite well on a 302/ 351...

 

[Truckin4life]

So drop the 185 heads on a 351 and bam 400 ponies?

intake and carb as well...

Hmmmm.....

 

[O'Rattlecan]

I wish they had found a way not to switch over to carb.

Ryan

 

[Truckin4life]

MAF will get you along way. Aftermarket EFI systems are limited by the physical limits of the engine...

 

[F 150Cobra]

we have calculated my engine to produce 325-335 Hp ( flywheel) with Gt40 heads and headers and carb intake and comp cams... the heads are holding me back BIG TIME!!

weight . mph in 1/4 is the way we calculated it