Blackdog36

iTrader: (3)

Need some input on my engine build/car goals. Keep changing my mind more I look into it. Just like every other person on here

Want car to have with decent street manners that I can drive on highway and to shows. Also want to tear it up at 1/8 and 1/4 drag strips. I've decided to yank out my existing engine, transmission, drive shaft and rear end for storage. Already have spare 700r that I can build up. Will bite the bullet and by a moser 12 bolt rear with a good driveshaft. Engine is what I am contemplating now.

I have a FIRST TPI intake and have been thinking that a 383 stroker would work nicely. Found that speed shop in my area sells cleaned up 350 blocks that I could get in "ready to go" shape for $600-$700. It would be nice to build bottom end strong enough to handle a 100-150 hp shot of nitrous in case I want some more power later on. Even without nitrous, it is not too much more to get a nice forged rotating assembly. I came across a basic bow tie block from Skip White.
http://www.skipwhiteperformance.com/...Item=1183-BLCK
They will bore it to my requested size (up to 4.155in) and ship to door for around $1,150. I believe they sell for $600 not machined. There are better aftermarket blocks out there but if I am not looking for crazy rpm and only some nitrous, seems to be a good deal. With that block I could make a 400, 406, 427 or 434 stroker since I am going to buy a rotating assembly regardless.

My question is will a 400+ SBC be too much for even a FIRST TPI intake? I know stock FIRST will work but will it move torque boost and power band down too low so that engine is dying past 5,000 rpm? Ideally FIRST runners should be ported to allow more flow for larger engine. Smallest item on FIRST unit are runner diameters at 1.75". Only flow numbers I've seen are 300 cfm for the manifold base. Thinking that runners would be around 280 cfm since they are smaller diameter than base openings. To me it seems that if I am going through trouble of getting a new/used block, rotating assembly, transmission and rear end why not go for a large cube SBC. Thoughts?

Pwnage1337

I think the FIRST will keep up fine. Those runners have lots of meat that you could port the hell out of too, there is a thread somewhere where somebody is running a hogged out super ram on a 406. the FIRST and Super Ram have the same flow abilities, except the FIRST can be ported more.

1989GTATransAm

iTrader: (3)

"I think the FIRST will keep up fine. Those runners have lots of meat that you could port the hell out of too"

I agree. The runners will be the key. If you can siamese them and leave maybe 1" of runner and open up the last 1" to say 1.9" ID they will flat out do the job. The intake manifold portion can flow enough right out of the box to handle 600 horsepower. Open it up some and get even more. At that point the heads will be the restriction.

Blackdog36

iTrader: (3)

Thank you for the responses. I appreciate it. Think I will go with a 400+ sbc. I've been reading what I can find online about 400+ engines with TPI. Will have to check some calcs to determine tuned rpm but it looks doable. Most people that try TPI on large sbc's do not have a FIRST unit.

I don't think I will be siamesing FIRST runners. Too much of a pain. Bend point halfway in runners is the choke point and hard to get at it. I am just going to sand what I can with my fingers to smooth out interior walls. I will grind down end of runners so they match gasket openings. I've attached a pic showing gasket on lower runner end that would match up to manifold base. Gasket has diameter of 1.875 inches. You can see that I need to grind a little to make a good match. I figure since TPI creates reversions back and forth through runners, that a smooth transition will really help flow for any engine size I end up with. Manifold base is pretty well designed and doesn't have that many bend restrictions. I'm just smoothing out what I can on the manifold too with sandpaper.

I measured lengths of tube and manifold runner lengths. Tubes are around 8.75" and manifold is 7.5" for total length of 16.25". This is length from plenum entrance to manifold exit. I found this link comparing different intake lengths that states "Accel super ram manifold 8” runners 7” cylinder head 6” total 21”. Adding 8"+7" yields 15" compared to 16.25" for FIRST. I think FIRST will work well since it flows better than Super Ram but has slightly longer runner length.
http://hobracing.com/tech/tpi_flow.asp

I have Lingenfelters book and forgot that he mentions good results with Super Ram on 406 and 420 sbc's. I did search for 434 TPI and found this company selling one with a FIRST intake. Way over priced but here is what they list for power. "Makes 450hp @ 5000 RPM and 575tq @ 4000 RPM".
http://www.precisionraceengines.com/...e-monster.html

AFR competition 195's look pretty interesting for a 400+ sbc. I think it would be pretty cool to have a TPI looking engine and nobody knows that it's a large sbc .

1989GTATransAm

iTrader: (3)

Looking over the list of the cfm ratings of the individual components remember that the total airflow will most likely be somewhat less than the most restrictive component in the air path.

The AFR 195 Competition heads flow over 300cfm. That is enough to support over 600hp. That will also give wicked throttle response with a 400ci motor. Your tires are not going to like you.

The ideal situation would be to have the runners flow around 320 cfm. Maybe spend the money and have them Extrude Honed. I would work the entrance and exits on the ports first and get them close to what you want.

Couple of thoughts. I would shoot for around 11:1 compression, .035" to .040" quench and maybe the XFI 292 camshaft. The cubic inches and the compression will eat that camshaft up and make it purr like a kitten at idle. Give it some throttle and you will think you have a lion by the tail.

If you want the fastest naturally asperated TPI car I know of we have a guy here in SoCal that can port the intake manifold and runners. That will give those AFR heads all the CFM they can handle. Providing you have a decent exhaust system and can hook up the tires I bet you would have a 10 second ride in the quarter mile

Blackdog36

iTrader: (3)

Looked into some calcs last night. Stock FIRST unit will hit 4th wave harmonic at 4,250 rpm using Comp Cam 292XFI and 16.25in intake length per this formula L = ((EVCDx.25xVx2)/(rpmxRV))-.5D

Using that RPM and stock runner cross area of 1.75in (2.41sqin), FIRST is tuned for a 400 ci engine out of the box. I would have to port runners out to 1.825in (2.62sqin) to get proper 4th harmonic tune on a 434 ci eninge.

195 AFR heads with cross sectional area of 2.18 inches will only support 5,500 rpm on a 434 ci before they cause problems. May have to got to 210's with 434. I looked into extrued honed and it seems interesting. Runners are around $200 but process does not really port them all that much, just makes it extremely smooth. Might see if I can get a drill extension and some sanding flapper wheels to port out the runners.

310cid

iTrader: (1)

what knock sensor did u suse i will be put a 90-92 computer on it

Blackdog36

iTrader: (3)

I haven't gotten that far yet. I thought stock sensors would work - only need early 80's truck style EGR valve.

InjectorsPlus

iTrader: (1)

Why would you want an engine that tops out at 5000 RPM? I think you can use the cam to move the power curve up.

And 195 heads aren't big enough, unless you're a landscaper and this is for your truck. If you insist on settling for an AFR head, look at the 210s. If you want to select the RIGHT head regardless of brand, there are other considerations. For example, Profilers are $250 less and you will give nothing up. Just sayin. Don't get sucked into the cliche's, it's not all about flow.

Doom86

I like the idea here but if you don't mind my I would go bigger with the heads. The 210 Profiler or 220 Air Wolf (what i'd choose) are better choices for a big sbc.

The Air Wolf line are just awesome. The "out of the box" head compares to CNC because of the casting technology they use. This is true for all the Profiler heads, not just the Air Wolf line.

InjectorsPlus

iTrader: (1)

Just another note, I wouldn't trust anyone who recommended the same parts for every build. I don't care if it's the same tire, heads, thermostat, exhaust, whatever. Anyone who spews the same answer to every question is not to be trusted...

Just keep your eye on that, it will save you money and yield you different results.

Blackdog36

iTrader: (3)

Thanks for the head advice, I'll look into the other ones. I was never set on 195 head size. Just a good starting point I was familiar with for a 350/383. I looked into head size a little more since my last post in October. An AFR 220 cc or similar head would work better since it removes limiting port velocity of head on 400+ cubic inch engines. Larger heads can also fit 4.125 inch cylinder bores which helps unshrouds the valves.

The 434 TPI turn key engine I posted above seems to be low on power for components used. I posted it since I was surprised that somebody was selling a large sbc with FIRST intake.

I've done a lot of research into tuned port harmonics and calculations. FIRST TPI intake length primarily dictates "tuned" rpm value. Cam duration affects tuned rpm band somewhat and runner diameter has even less. Cam duration stills needs to be in a certain range to match engine size, cylinder heads and usage. A FIRST TPI unit slightly ported with a 292 duration will create tuned rpm effect at around 4,350 rpm for the 3rd harmonic wave. 2nd harmonic wave would create a better tuned effect but it would do so at 6,500 rpm. The runner diameters could not be opened wide enough to feed a 400+ engine at this rpm and still create maximum tuned effect. What I found is that FIRST length and runner diameter would be best matched to 4,300 rpm, with 292 duration cam on a 414 +/- cubic inch engine. I am not looking for a high rpm screamer engine. I knew this going in before I bought my FIRST intake.

From what I've read about the Dart SHP block, it is tough to make it a 434 with 4 inch stroke. I might have to back down to a 414 or 427 to play it safe. It would be nice to have an all USA rotating assembly but ones needed to work with long stroke are expensive and few in choice.

355tpipickup

iTrader: (5)

How do you do the calculations to findout what the tuned RPMs would be on a cam the motor size? I would like to findout what the info would be on a 355-383 with a 224-230/230-236 cam with the FIRST

1989GTATransAm

iTrader: (3)

Heck the 427 would be just fine with me. For what you are doing the problem with the First is how to open up the runners. The base is not the problem as it can readily opened up. The plenum is not a problem either.

One thought on the runners is to make sure they are at the minimum of 1.75 inch diameter where you can get to it. I have measured some of the inside of the runner and it appears to be a little larger that the 1.75 at the ends.

One method I have thought of is Extrude Hone. That will take .040 off of each side for a total of .080". That would increase the ID of the runner to 1.83 square inches. That would help things quite abit.

Here is a online runner length calculator for wave tuning if you have not seen this one yet. http://www.bgsoflex.com/intakeln.html

Blackdog36

iTrader: (3)

355tpipickup - I'm close to wrapping up some nice excel sheets with graphs that shows best tuned rpm for different sized engines and cam durations for a FIRST, stock TPI and Accel Superram intake. I'll post a separate thread soon in this section with the info.

1989gtatransam - Although ends of FIRST runners are large, I cannot fit a golf ball through since they get narrow at bend in middle. Golf ball is 1.68" diameter so I will have to open up runners some. Extrude hone looks nice but not sure if I want to spend money or try some sanding. Honing is about $300 for runners. Thinking sand flapper wheels on drill extension might work.

427 does have a nice ring to it. Would need max bore on Dart SHP block with 3.875" stroke. Might back bore down some to get a 414 or 420.

1989GTATransAm

iTrader: (3)

Runners #1 and #8 are narrower in the middle. #1 to miss the water jacket and #8 for distributor clearance. However I had not problem opening them up. Plenty of meat to work with. You will have to configure the runner CSA to the size of the motor you are working on.

I think you can get access to most of the First runner but maybe part of the inside middle area.