Hi there! I have a couple quick questions.

First off I had planned on doing an LS swap, and then turboing that with a gt45, shooting for around 550-600. However I've found an already built car for less than I could build the other. It has a 475 hp, stock block 406 SBC with 10.5 Compression with the dyno sheet to prove it.

So considering the cars already together, and I already bought all the turbo parts I figured I could just turbo the 406. I haven't found a whole lot on blow through, and how to set timing, but is 10.5 too much compression for boosted applications?

Otherwise my other option is to pull out the 406 and try and sell it and go with my original plan.

Thanks!

 

HI there, start by reading my article it may help you and I will type further to help you as well.

To start with please tell us what your application and vehicle is? Car, truck, weight? Use of the vehicle?

10.5:1 static compression is not necessarily too high for boost, however it does not give you a large tuning window, the tune must be VERY VERY good, where as with 8:1 there is a much larger tuning window.

There are several options you can look into so that you can make your engine work well with boost:

1. Keep the engine the same and run VERY low boost and no intercooler. This would be a simple setup, and 3 or 4 PSI will give a very good gain over what you have now. With such low boost the charged air temps are low enough to be fine without the intercooling.

2. Swap the heads to a larger chamber to lower the compression to about 9:1, which tends to be the sweet spot between giving a good tuning window and also not giving up too much "off boost" torque. You could also swap pistons and or head gaskets however asuming you have a good strong bottom end I would not touch it with the exception of a custom turbo cam. Keep in mind that you want to keep your "quench" distance tight so thicker head gaskets may not help at all.

3. E-85 is another option. If you can get this in your area then go for it, convert your fuel system to work with the E-85 and boost the 10.5:1 engine as it is. E-85 also works well without an intercooler so many people like that.

For the blow through carbs they can work very very well. You can google the "hanger carb mods" and do it yourself or you can call CSU and they can make you a custom carb that will bolt on and be VERY close to perfect right out of the box. I used a CSU carb and it was pretty much perfect in all conditions and driving ranges, I was impressed! The $ I spent on the carb I saved in less dyno tuning needed and less risk to my combo with a self done carb setup.

For the timing the general consensus is that the programmable MSD style boxes are the best way to dial in the timing curve, however there are also guys like me running a locked out timing with no mechanical advance and then a vacuum advance canister to add timing at part throttle. Of course I am leaving some part throttle power and fuel mileage on the table with my crude locked out timing however the car is crazy even with less than ideal timing curve....

And a word of warning... I took a stock piece of shit 350 and added 10 PSI and it turned into a tire shredding monster, you have a healthy V8 that even with just 5 PSI of boost will be breaking transmissions and rear ends in no time! NOw have fun and keep us posted....

BTW there are many people on here with more racing experience than me, so stick around, start a "build thread" in that section and start taking notes.... OH and post pics!!




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it definitely can be done. My old motor was a 10.5 (gen1 2 bolt) sbc 383. I ran it at 8-9psi intercooled with no problems for years (still fine, but in my garage) on pump gas. Currently have a 406 9.5:1 running 11psi with the same 80mm Chinese GT45. It may be hurting the top end a bit with the smaller turbo for the CI but mine is a 5speed street car.

highly recommend C&S aerosol blow thru curb. no problems with mine.... EVER. Tell them your setup and it comes almost spot on. A little tweaking and your perfect (install a wideband O2 for safe monitoring and tuning).

I use the MSD programmable 6530 computer. Lock distributor at max advance timing (i do 33-34) and use the box to make a timing curve based on boost. (safe is 2/psi to start and a max of 18 degrees pulled). The only RPM based curve i have is pulling 15 degrees out from 0 rpm to 500 rpm to allow for easy cranking when hot.

good luck. don't get greedy on your boost or tune and you'll be fine.

chris

 

I didn't read all that, the article i have read before, but plan on at least a cam swap, something with a lot less overlap, and a very late intake closing. If you can score a good deal on some 76 cc aluminum heads, preferably something with excellent exhaust flow like AFR heads, then you will be limited by the block itself, if it is a production block. If so, it can't take 900 horses, which any and all of the LSx blocks can. You could probably sell that 400 for enough to get an LQ4.

 

Have you thought about looking into the Fitech stand alone? I have a buddy with a similar set up running Fitech and he loves it, it seems to work really good, he runs the top kit which was $1200 and will support 1400 horse and comes with everything you need

 

Thread is almost a year old lol