I'm getting ready to build a 406 for my GTA and I want to run a max-ported stock plenum, ported Accel runners and ported Edelbrock base. Looking for someone who has actually done this and I would like to hear about your experiences (traction, top-end, etc.) Thanks.

 

i haven't done it personally but know people who have and i can tell you keeping the ltr design is not gonna cut it so before you put it together to take it apart if your gonna keep the design definatly siamese the openings on the plenum aand get a set of slp or edelbrock runners and siamese them to effectivly shortening the runner length from a god awful(horsepower that is)22 inches to about 6 3/4 should help you fill that huge cannon hole of a cylinder quicker

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87 trans am 350 L98 aluminum heads,LT4 hot cam,slp runners,headers,y-pipe,edelbrock base,hi flo cat,air foil,ported plenum,t-5 tranny w/centerforce clutch and a 3.27 9bolt,ads strip chip,relocated iat sensor,hollowed maf

14.10@97mph w/2.01 60' 4SALE anyone want her?

 

They weren’t the Accel LTR’s but I did build one using the Edelbrock runners on a friend’s 406. Pretty much a budget deal with the LPE 74213 flat tappet cam. Heads were Dart Sportsman II’s with mild port They’re both practically the same with the exception of the funky designs on the outside of the Edelbrock’s. The lower was a fully ported Edelbrock piece also. He had 3.45’s in the rear along with Bowling Green Customs’ (known by the turbo GN crowd) racing recaps. Lots of torque down low. With the BGC tires, traction wasn’t all that. Definitely needed slicks at the track for the best performance. The car saw high 12 time slips. The saw power in the 5600-5800RPM range. Real good for a street car. Haven’t seen how fast top MPH is though. You got to figure that before he created the Superram, Lingenfelter was building 180+ MPH 383’s with long tube runners that ran mid 12’s all day. Long tube runners can’t be all that bad.

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N/A 406, TPIS Miniram, 58mm TB, 30lbs injectors, Custom Ground Elgin Cam, Ported TFS heads, SLP 1-3/4", & DFI computer.
11.70@117mph

 

Just wanted to say that I am in the process of doing the same thing. Just came across a good 400 block so going with that. I have the SLP runners, porting the base, going with big TB, etc... My hangup is... Are you going with a custom chip? I am considering buying another TPI unit just to work on tuning the FI on the engine stand. What are you doing as far as adapting the TPI to the 400?

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Mint black/black 1987 T/A GTA 305 5-speed, 55K,
3.45 factory POSI,SLP cam, SLP runners, Taylor wires, hurst comp plus shifter, K&N conical rig, AFPR, coated shorty headers, no cat, no smog, 3in. mandrel-bent single exhaust, flowmaster, TB air foil, 160 stat, SFC's, lower control arm adapters, Aluminum Driveshaft, ported upper and lower, Mobile ES and 10 disc, kickers all around and q-logic kick panels...Perf 350, rear batt, lowering springs,cowl hood, & NOS coming soon!

 

Actually, the TPI is easy to physically set up on a 400. You just have to take the intake base bolt pattern into consideration. 87-92 Gen II intake bases have a "non-conventional" pattern and will work only with Gen II style heads, while 85-86 bases will work with all heads 86 and earlier. Aftermarket bases are machined to work on both styles of heads.

I don't know how versed you are with the 400, but the stock heads are considered junk for performance applications. I wouldn't waste any time or money on them.

The main reason I want to use the LTR setup is because I already have it on my 305 with a pair of L31 heads. I really wanted to go el cheapo with the 400 and just freshen it up and drop it in, but I eventually plan on a Miniram somewhere down the line and I don't want to pull the motor back out to build it right.

Instead of going low-buck with the shortblock, I'm going to have the crank mains turned .010, 5.7 rods will be used with forged pistons +.030, and I'll have a 10.5:1 CR with Gen II style AFR heads. I'm also going to use a custom chip with 24 lb. injectors and a 58 mm TB.

I would strongly suggest going with an aftermarket base. Stock bases have pathetically weak flow and would severely limit the 400 all around. The Edelbrock made a helluva difference on my 305, so I can imagine the difference with another 100 cubes.

I figure traction to be a big problem on the street (already is with the 305), so I hope LCA's and an adjustable torque arm will help a bit.

Jason
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87 GTA LB9/R4/3.23s
Black/black cloth int.
L31 heads, ZZ4 cam, SLP headers, and lotsa other stuff!